NOTE- The steps below are the same for Auth PRO and Utilities PRO Packs.
1. Go to Firebase Console Project Settings. Add an Android App if you dont have already.
2. Copy app Package Name.
3. Download the google-services.json file.
You had copied the Package Name in the last step.
Now, in your Construct 3 Project Properties, paste this value in ID.
Import google-services.json to Files in your Construct 3 project.