Logging into Ring Central Phone app - only one user can be logged in at a time.

HI, I work in IT support for a small CRM, and we are testing out RC with our CRM. The issue we are having is that two users, my boss and I, cannot be logged into RC and making calls at the exact same time. Even with separate logins it will only allow one user to be logged in at a time. Can anyone shed light onto why this could be happening?