Hi @jgh,
Welcome to the Auth0 Community!
Unfortunately, the Authorization Core does not yet support groups, as mentioned in this documentation.
However, I found an existing Product Feedback request asking to support groups in the Authorization Core, which I strongly recommend upvoting so that we can prioritize implementation based on the highest votes:
For now, if you still require using Groups, you could continue using the Authorization Extension. As for its deprecation, we currently don’t have a concrete date on when this feature will stop working, but when that happens, we will make an announcement about it.
Thanks,
Rueben