The error is:
File google-services.json is missing from module root folder. The Google Quickstart Plugin cannot function without it.
For using Google SignIn in Android app, you need
google-services.json
which you can generate using the instruction mentioned here
It should be on Project -> app
folder
Please find the screenshot from Firebase website
WINDOWS
(Alt+F12 or View->Tool Windows->Terminal).
Then type "move file_path/google-services.json app/"
without double quotes.
eg
move C:\Users\siva\Downloads\google-services.json app/
LINUX
scp file_path/google-services.json app/
eg:
scp '/home/developer/Desktop/google-services.json' 'app/'
Click right above the app i.e android(drop down list) in android studio.Select the Project from drop down and paste the json file by right click over the app package and then sync it....