If I try to connect to the local server (replica), I can see updates, but I can’t modify or create updates.That's a normal situation. This is how Replica works. you can't change anything on a replica (except deleting updates). You will never be able to publish directly to the replica or approve directly to the replica. Replica server are manage by the upstream server.
If I add my account on the administrators group of upstream server, no problem.To manage a Wsus server with WPP, you need to be in the Wsus administrators group.