create app in google developer console, enable google plus api
Also make sure to create in firebase
reverse_client_id is only needed for iOS and could be get from plist file that can be generated by creating an new ios app in google developer console (GDC) and downloading the plist file.
for android, make sure to create SHA1 for debug and production both by running the keystore command and add it to the firebase app by going to the app settings from overview.
now get the reverse_client_id from plist file and install the cordova plugin. as well as the node package.