This is some tutorial of firebase. I\'m registering app in Firebase, getting the google-services.json file, pasting it in the app files as shown in the tutorial. Also getting th
May be you're not add a correct SHA1 for your application?
you can follow this tutorial to get the correct SHA1. And then on console firebase choose project setting, choose add SHA1. After that, you need to replace google-services.json with the newest one.