Tried to create GKE cls, got error message: Service account “515803842356-compute@developer.gserviceaccount.com” does not exist. Does this have something to do with billing?

Hello!  I’d like to start by pointing out something related to your comment that might seem a bit pedantic but is actually important: You don’t actually do things in your trial account, because that’s a billing account.  Rather, you do something in a project which might happen to be linked to your trial billing account.  So that leads me to my question that I hope will help you get unblocked…

Are you doing this–creating the GKE cluster–inside your networking project or in another one?  I would recommend that you use a new project for this GKE stuff–or at least your "Services Exploration Labs" one–because we messed around with the service accounts in the networking project and that could cause this error.

Cheers!

Mattias