You can add any number of new team members.
If you want to want to add team members, purchase an Add-on through the Subscription system, for that number of users.
Remember to activate them, after entering their details in the Manage User module. Also, ensure they have been allocated their correct role.
Roles are created through the Manage Role module. While there are three default roles given (Admin / Uploader /Transcriber), you can choose to create any Title you wish. For example, in a school, you could create roles such as Admin / Nurse / Tutor / Coach. And permissions for each Role can be issued here.
All newly added team members have to be allocated to a specific team or teams. Initially, everyone is added to a common pool. This is through the Manage Teams module. Using the school example, teachers teaching different ages could be made the members of specific class teams.