Can't get .aab build because of Gradle error

Hey everyone. So I'm trying to get a build for my game on android. I had no problem getting .apk builds but when I tried to get .aab builds to put on the Playstore I faced with some issues. I tried many of the solutions on the internet. It still doesn't work. So here is the last error I got.

 Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF-8
 
 FAILURE: Build completed with 2 failures.
 
 1: Task failed with an exception.
 -----------
 * Where:
 Build file '/Users/ykcalikoglu/Desktop/Unity Projects/ToyRun/Temp/gradleOut/unityLibrary/build.gradle' line: 72
 
 * What went wrong:
 A problem occurred evaluating project ':unityLibrary'.
 > Could not find method classpath() for arguments [com.android.tools.build:gradle:3.4.3] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.
 
 * Try:
 Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
 ==============================================================================
 
 2: Task failed with an exception.
 -----------
 * What went wrong:
 A problem occurred configuring project ':unityLibrary'.
 > compileSdkVersion is not specified.
 
 * Try:
 Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
 ==============================================================================
 
 * Get more help at https://help.gradle.org
 
 BUİLD FAILED in 23s
 
 UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /Users/bokken/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:189)