Can't log into Google Drive to embed a Sheet

Question

I installed the official Confluence Google Drive app, and embedded a sheet into my document (using the sheet's link). I see the login page:

but when I click on the "Sign in to Google" button, nothing happens. What else do I need to do to make this work?

Note I log into Confluence via Atlassian's SSO, not my Google Account.

Thanks.

Chris Livadas · Answer

Maybe it's a Firefox issue. So I enabled cookies for the atlassian.net domain and now I get redirect message with a spinner that never ends: