I am trying to integrate Firebase Cloud Messaging (FCM) into my Android app, but I am stuck at Step 2: "Add FCM to your app" in the Firebase Assistant in Android Studio.

When I follow the setup wizard, it installs dependencies and updates my project. However, after installation, the "Add FCM to your app" button remains disabled, and FCM is not properly added to my project. I tested this on three different devices and also targeted newer Android versions, but the issue persists. I have followed four different YouTube tutorials and all steps in the official documentation, but nothing has worked so far.