In order to add an additional user, you must go to the Users page within Settings. Once in the Users page, please click "Invite User". Add the individual's first and last name as well as their email address. Finally, select the correct role for the individual (admin vs property manager).
The property manager role can be selected if the individual user needs to have access to applications for specific properties or if you would like to limit what the user can do in the portal. The screenshot below shows all of the customizable features that can be activated for property managers.