How to add fragment activity to MainActivity.java or MainAcyivity.kt

I am trying to build fingerprint fitur in my flutter apps and I am using local_auth package... the problem is that I always get below error-

PlatformException(no_fragment_activity, local_auth plugin requires activity to be a FragmentActivity., null)

I try to add FragmentActivity to MainActivity.kt but it doesn't work.. here is the structure of my folder... so should I create MainActivity.java? and where should I place MainActivity.java in my folder?

and here is the content of my MainActivity.kt

package com.project

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

Here is how to do it with Kotlin

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterFragmentActivity;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugins.GeneratedPluginRegistrant;

import android.os.Build
import android.view.WindowManager
import android.view.ViewTreeObserver


class MainActivity: FlutterFragmentActivity() {
  override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
    GeneratedPluginRegistrant.registerWith(flutterEngine);
  }
}