First i purchased the WebViewGold app template

The I followed the official documentation

 

To setup Firebase I followed the awesome tut:

Firebase

1. Create new project
2. Step 3: Register Your App

   Click Register app to complete the registration process.

   Step 4: Download GoogleService-Info.plist

   Download this configuration file and replace the placeholder in your WebViewGold project with the downloaded GoogleService-Info.plist file.

   Step 5: Activate Firebase in WebViewGold

   In the Config.swift file, set the kFirebasePushEnabled variable to true to enable Firebase functionalities.

3. Step 6: Set Up APN and Sign Your App

   Generate an APN key for Firebase, upload it, and then sign your app using the Firebase provisioning profile. For a detailed guide, visit Firebase documentation on iOS certificates.

4. Declare Your App’s Use of Encryption –> ITSAppUsesNonExemptEncryption  –> NO