That error message appears because the email address or phone number used to register the resident is already registered in the Yipy system. This means the resident has most likely created an account before, either for the same unit or for a unit in another property that also uses Yipy.
In this case, the Property Manager does not need to create a new account. As a solution, the Property Manager can ask the resident to log in with their existing account and then submit a Request Premium to connect to the correct unit. Once the Property Manager approves the request, the resident will automatically be connected to the unit without having to register again.