the request is missing a valid app identifier firebase

I am looking for a freelancer who can integrate Firebase into my existing Android app.

Platform: Android

Ideal skills and experience:
- Experience with Android app development
- Proficiency in integrating Firebase into Android apps
- Familiarity with Firebase features and functionalities
- Knowledge of Firebase project setup and configuration

Project requirements:
- Integrate Firebase into my existing Android app
- Ensure a valid app identifier is provided for Firebase integration
- Connect the app with an existing Firebase project

Note: The client already has an existing Firebase project.