How to launch unity android app on startup?

I have seen similar questions but I can't get it working, either because I lack some basic knowledge or because I am missing in between steps.

I have also checked the plug in build manual and found no answer, it exposes several methods to execute native code, using DLLs, using "androidJavaObjects" created in c# scripts and using java classes. This third method seemed the simpler so I went with it. This is what I have done:

-Create in the Plugins folder and Android folder, placed this AndroidManifest.xml there: http://schemas.android.com/apk/res/android">

   <uses-permission android:name="com.test.app.permission.C2D_MESSAGE" />
   <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
   <uses-permission android:name="android.permission.WAKE_LOCK" />
 
   <application android:label="@string/app_name">
     <receiver android:name="ReceiverOnBoot" android:enabled="true"
        android:exported="true" android:label="com.InteractionFactory.startingtest.ReceiverOnBoot">
           <intent-filter>
               <action android:name="android.intent.action.REBOOT" />
           </intent-filter>
           <intent-filter>
               <action android:name="android.intent.action.BOOT_COMPLETED" />
           </intent-filter>
     </receiver>
  
 
   </application>
 </manifest>

-Create an "ReceiverOnBoot.java" file with those contents pakage com.InteractionFactory.startingtest;

 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 
 public class ReceiverOnBoot extends BroadcastReceiver {
 
     @Override
     public void onReceive(Context context, Intent intent)
     {        
         intent = new Intent(Intent.ACTION_VIEW);
         intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         intent.setData(Uri.parse("market://details?id="+packageName));
         startActivity(intent);
     }
  }

I have tried replacing the "onReceive" function contents with "Toast.makeText(context, "TEXT TO DISPLAY", Toast.LENGTH_LONG).show();" for debug purposes, to no effect.

Also, since I added those files no icon is created when I install the apk.

Do I need to compile the "java" file in any way? Build "jar" files maybe?