Hi there.. Stuck since days in the google auth error:disallowed_useragent with xamarin, my colleagues ask me to ask to u :p (the same as the mac with windows features photo)

Google has changed its policy, you cannot authenticate using webviews anymore. I would suggest leaving the shit out of xamarin.auth and using GooglePlayServices.Auth, which works better and is recommended and documented by Google. Have a nice day, despise xamarin's shittyness :D