FireBase stuck on "Run your app to verify installation" for android

You have to do nothing for your question but run the app on the android emulator or a real android device. If you have made your app and later added the dependencies, then you need to delete the app from the device/emulator and install the app again.

By doing this, when the app runs, it passes variables from the google-services.json file to the firebase servers and checks if the same app is communicating or not.

This step is to verify the correct installation of firebase dependencies in the app. If you find it difficult, you can skip the process anyway.

Thanks to @Udayraj Deshmukh comment I fixed the issue. I thought I will add this as an answer as it helped me

Simply go to your app-level Gradle and add this:

apply plugin: 'com.google.gms.google-services'

Firebase SDK guide forgot to tell you to include the plugin.