This Sign in page is load from Google.com, my app don't know your password of Google.
Sign in again when your want to change to other account of Google.
Press 'ALLOW' button, and waiting for next step.
Don't press any where, the sync will action after Sign In successful.
Press 'Confirm' button when you want to action those suggestion.
This step need some time.
Run sync again to check all contacts after first sync.