Getting NoClassDef Found Error when creating android plugin for amazon login

I was trying to integrate the LWA (Login With Amazon) SDK into a sample unity project that I created. but I am getting the following error when I created the APK from Unity. Is it a versioning problem?

2021-10-22 14:52:45.800 17549-17578/? E/Unity: AndroidJavaException: java.lang.NoClassDefFoundError: Failed resolution of: Landroid/support/v4/app/FragmentActivity; java.lang.NoClassDefFoundError: Failed resolution of: Landroid/support/v4/app/FragmentActivity; at com.amazon.identity.auth.device.api.workflow.RequestContext.create(RequestContext.java:73) at com.example.unityamazonplugin.AmazonPlugin.SetupSDK(AmazonPlugin.java:27) at com.unity3d.player.UnityPlayer.nativeRender(Native Method) at com.unity3d.player.UnityPlayer.c(Unknown Source:0) at com.unity3d.player.UnityPlayer$e$1.handleMessage(Unknown Source:95) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:236) at com.unity3d.player.UnityPlayer$e.run(Unknown Source:20) Caused by: java.lang.ClassNotFoundException: android.support.v4.app.FragmentActivity at com.amazon.identity.auth.device.api.workflow.RequestContext.create(RequestContext.java:73) at com.example.unityamazonplugin.AmazonPlugin.SetupSDK(AmazonPlugin.java:27) at com.unity3d.player.UnityPlayer.nativeRender(Native Method) at com.unity3d.player.UnityPlayer.c(Unknown Source:0) at com.unity3d.player.UnityPlayer$e$1.handleMessage(Unknown Source:95) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:236) at com.unity3d.player.UnityPlayer$e.run(Unknown Source:20) at UnityEngine.AndroidJNISafe.CheckException () [0x00091] in :0 at UnityEngine.AndroidJNISafe.CallVoidMethod (System.IntPtr obj, System.IntPtr method

Plugin Class Code -

 package com.example.unityamazonplugin;
 
 import android.content.Context;
 import android.util.Log;
 
 import com.amazon.identity.auth.device.AuthError;
 import com.amazon.identity.auth.device.api.authorization.AuthCancellation;
 import com.amazon.identity.auth.device.api.authorization.AuthorizationManager;
 import com.amazon.identity.auth.device.api.authorization.AuthorizeListener;
 import com.amazon.identity.auth.device.api.authorization.AuthorizeRequest;
 import com.amazon.identity.auth.device.api.authorization.AuthorizeResult;
 import com.amazon.identity.auth.device.api.authorization.ProfileScope;
 import com.amazon.identity.auth.device.api.workflow.RequestContext;
 
 public class AmazonPlugin {
 
     public static final  AmazonPlugin pluginInstance = new AmazonPlugin();
     public static AmazonPlugin getInstance() { return  pluginInstance;}
     private boolean loginSuccessful = false;
     private RequestContext requestContext;
     private AmazonPlugin(){
         Log.i("Xansr", "Created Log Plugin");
     }
 
 
     public void SetupSDK(Context unityContext){
         requestContext = RequestContext.create(unityContext);
         requestContext.registerListener(new AuthorizeListener() {
 
             /* Authorization was completed successfully. */
             @Override
             public void onSuccess(AuthorizeResult result) {
                 /* Your app is now authorized for the requested scopes */
                 Log.i("Log", "Logged in success " + result.getUser().getUserEmail());
                 loginSuccessful = true;
             }
 
             /* There was an error during the attempt to authorize the
             application. */
             @Override
             public void onError(AuthError ae) {
                 /* Inform the user of the error */
                 Log.i("Log", "Logged in error");
             }
 
             /* Authorization was cancelled before it could be completed. */
             @Override
             public void onCancel(AuthCancellation cancellation) {
                 /* Reset the UI to a ready-to-login state */
                 Log.i("Log", "Logged in cancel");
             }
         });
     }
 
     public boolean isUserLoggedIn(){
         return  loginSuccessful;
     }
 
     public void LoginPressed(){
         AuthorizationManager.authorize(new AuthorizeRequest
                 .Builder(requestContext)
                 .addScopes(ProfileScope.profile(), ProfileScope.postalCode())
                 .build());
     }
 
 }

Unity Code -

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using TMPro;
 
 public class PluginTest : MonoBehaviour
 {
     const string pluginName = "com.example.unityamazonplugin.AmazonPlugin";
     static AndroidJavaClass _pluginClass;
     static AndroidJavaObject _pluginInstance;
     public Button LoginButton;
     public TextMeshProUGUI LoggedInText;
     public static AndroidJavaClass PluginClass
     {
         get
         {
             if(_pluginClass == null)
             {
                 _pluginClass = new AndroidJavaClass(pluginName);
             }
             return _pluginClass;
         }
     }
 
     public static AndroidJavaObject PluginInstance
     {
         get
         {
             if (_pluginInstance == null)
             {
                 _pluginInstance =PluginClass.CallStatic<AndroidJavaObject>("getInstance");
             }
             return _pluginInstance;
         }
     }
     // Start is called before the first frame update
     void Start()
     {
         LoginButton.onClick.AddListener(CheckAndSetLogin);
         SetupSDK();
     }
 
     void SetupSDK()
     {
         if (Application.platform == RuntimePlatform.Android)
         {
             AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
             AndroidJavaObject activity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
             PluginInstance.Call("SetupSDK", activity);
         }
     }
     void CheckAndSetLogin()
     {
         if (Application.platform == RuntimePlatform.Android)
         {
             PluginInstance.Call("LoginPressed");
             StartCoroutine(StartCheckingForLogin());
         }
     }
 
     IEnumerator StartCheckingForLogin()
     {
         yield return new WaitUntil( () => PluginInstance.Call<bool>("isUserLoggedIn"));
         LoggedInText.gameObject.SetActive(true);
         LoginButton.gameObject.SetActive(false);
     }
 }

build.gradle -

 apply plugin: 'com.android.library'
 
 android {
     compileSdkVersion 29
     buildToolsVersion "31.0.0"
 
     defaultConfig {
         minSdkVersion 16
         targetSdkVersion 29
         versionCode 1
         versionName "1.0"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         consumerProguardFiles "consumer-rules.pro"
     }
 
     buildTypes {
         release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
     }
 }
 
 dependencies {
     implementation fileTree(dir: "libs", include: ["*.jar"])
     implementation 'androidx.appcompat:appcompat:1.3.1'
     implementation files('libs\\login-with-amazon-sdk.jar')
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
 
 }
 
 task copyPlugin(type: Copy){
     dependsOn assemble
     from('build/outputs/aar')
     into('../../../../../Assets/Plugins/Android')
     include(project.name + '-release.aar')
 }