Top Level Group and Assigned Group

I have a project that was created under a groupA name. I have since started paying for 6 seats for groupB. The project has no members (other than me as owner). I have assigned groupB so people can work on this project. However, I am getting " Your top-level group groupA is over the 5 user limit and has been placed in a read-only state."

What do I need to do make it so that groupB can work on this project and there are no warnings?