https://news.ycombinator.com/item?id=45968731

  Why can I not authenticate into Google Antigravity?
  Google Antigravity is currently available for non-Workspace personal Google accounts in approved geographies. Please try using an @gmail.com email address if having challenges with Workspace Google accounts (even if used for personal purposes).

I love how being a paying Workspace customer for a decade or more has actually locked me out of so many Google products and features.

Not that I have any desire to try this at this point, but it's always felt ironic.

Thanks. Actually did use my personal account and got the issue nonetheless.