This is the error message that a 2nd user recieves when trying to login to the repository:
Log in failed because the number of sessions has reached the licensed limit, or the user account has reached its session limit, or no named user license has been allocated to the user account. [9030]
Seems like the repository is only seeing licences assigned specifically to the repository, and not the available licences in Rio for any repository, and this only started happening after moving the server VM to a new host server.