It sometimes happens that you can’t log into your Google account with 3rd party clients (e.g. a PC APK downloader). You just get a Bad Authentication error, telling you that your credentials are incorrect (even if they aren’t). What really happened is Google blocking your login attempt because it somehow “looked different” than usual and that triggered the intrusion detection alarm.
Solution: Log into your Google account with a web browser and go to it’s settings page. Check the list of last logins, a security alert should be shown there. Confirm that this was you. Afterwards you can sign in again with your 3rd party client.