How to set 1 team max + BLOCKED page

Hey!

Right now on my site people can create unlimited teams but I would like them to only be able to make 1 or if they are in a team then none. Is it possible to change that button to view team?

Also if people log into my site, they get a blank page with BLOCKED on it. It’s not because of the plugins, I disabled them without succes.

Any help?
Thanks in advance!