Unable to integrate Google Mobile Ads in Flutter

I've been struggling to integrate google ads in the flutter app. It keeps crashing.

Installed version: google_mobile_ads: ^0.12.1+1

I've updated the manifest too with the ads meta-data

<meta-data             android:name="com.google.android.gms.ads.APPLICATION_ID"             android:value="<AD-CODE>" /> 

Whenever I try to debug the code on the emulator. I get these errors in the console:

Launching lib/main.dart on sdk gphone x86 arm in debug mode... ✓ Built build/app/outputs/flutter-apk/app-debug.apk. E/AndroidRuntime(23372): FATAL EXCEPTION: main E/AndroidRuntime(23372): Process: com.example.kavya_digest, PID: 23372 E/AndroidRuntime(23372): java.lang.RuntimeException: Unable to get provider com.google.android.gms.ads.MobileAdsInitProvider: java.lang.IllegalStateException: E/AndroidRuntime(23372): E/AndroidRuntime(23372): ****************************************************************************** E/AndroidRuntime(23372): * Invalid application ID. Follow instructions here:                          * E/AndroidRuntime(23372): * https://googlemobileadssdk.page.link/admob-android-update-manifest         * E/AndroidRuntime(23372): * to find your app ID.                                                       * E/AndroidRuntime(23372): ****************************************************************************** E/AndroidRuntime(23372): E/AndroidRuntime(23372): E/AndroidRuntime(23372):    at android.app.ActivityThread.installProvider(ActivityThread.java:7135) E/AndroidRuntime(23372):    at android.app.ActivityThread.installContentProviders(ActivityThread.java:6675) E/AndroidRuntime(23372):    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6592) E/AndroidRuntime(23372):    at android.app.ActivityThread.access$1300(ActivityThread.java:233) E/AndroidRuntime(23372):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1896) E/AndroidRuntime(23372):    at android.os.Handler.dispatchMessage(Handler.java:106) E/AndroidRuntime(23372):    at android.os.Looper.loop(Looper.java:223) E/AndroidRuntime(23372):    at android.app.ActivityThread.main(ActivityThread.java:7523) E/AndroidRuntime(23372):    at java.lang.reflect.Method.invoke(Native Method) E/AndroidRuntime(23372):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) E/AndroidRuntime(23372):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941) E/AndroidRuntime(23372): Caused by: java.lang.IllegalStateException: E/AndroidRuntime(23372): E/AndroidRuntime(23372): ****************************************************************************** E/AndroidRuntime(23372): * Invalid application ID. Follow instructions here:                          * E/AndroidRuntime(23372): * https://googlemobileadssdk.page.link/admob-android-update-manifest         * E/AndroidRuntime(23372): * to find your app ID.                                                       * E/AndroidRuntime(23372): ****************************************************************************** E/AndroidRuntime(23372): E/AndroidRuntime(23372): E/AndroidRuntime(23372):    at com.google.android.gms.internal.ads.zzzt.attachInfo(com.google.android.gms:play-services-ads-lite@@19.7.0:24) E/AndroidRuntime(23372):    at com.google.android.gms.ads.MobileAdsInitProvider.attachInfo(com.google.android.gms:play-services-ads-lite@@19.7.0:3) E/AndroidRuntime(23372):    at android.app.ActivityThread.installProvider(ActivityThread.java:7130) E/AndroidRuntime(23372):    ... 10 more Exited