Unzip the zip file that you got from CodeCanyon ( if you haven't already ).
Open the file Mobile App with Visual Studio Code.
To download service account JSON file go in console.firebase.com then in Project -> Project Settings - > Service Accounts and click on "Generate new private key"
Extract the zip that you got from codecanyon. Save this file as service-account-file.json in Mobile App/Producer/service-account-file.json
Once again go in your Firebase console. Then go in Project Setting and create a web app. In the file structure, locate firebase_config.js. Copy the values from Firebase to you firebase_config.js.
In Visual Studio terminal run