Log back into your Google Cloud Console and under the Audience setup for the Google Drive API, you’ll see “Test users”, click “Add users” and add your email. Re-try setting up the connection and it should now present you with a warning where you could press continue.
Hey I faced the same issue, but later realised i missed the important step that we have to publish our app after configuring OAuth consent screen.
please check below link, and verify your process it will surely solve your issue
How to Connect Google Drive with n8n (Without OAuth Errors)
if there’s still the issue, please inform