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when I do that I choose a web app Client ID.
I'm afraid the Application type is Desktop not Web App. You could try to create a new Client ID which Application type is Desktop.
I test it by selecting Desktop, it wroks, you could have a try.
For more information, you can refer to
https://developers.google.com/identity/protocols/oauth2/native-app#android
https://stackoverflow.com/questions/64576758/error-400-redirect-uri-mismatch-when-distributing-xamarin-forms-app
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update--------------
Google has been fairly consistently changing the oauth configuration workflow. For this Error 403: access_denied
you have to add your account as a test user which will allow you to authorize. You can do it like this : ** Go to your Goole developer console, click Users and permissions, then add the user for App permissions and Account permissions. **
Best Regards,
Wenyan Zhang
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