There are three different types of users within Creative Force. Full-Time, Day Pass and Resource Users.
Full-time users are for people in your organisation that always need to have access to Creative Force in their day to day work. People like an Art Director, Studio Manager or a Product Owner.
Day Pass users are typically free lance team members who do not need to Creative Force on an ongoing basis. This could a part time or free lance Stylist, Photographer or Retoucher.
Resource Users are users that do not need to use Creative Force in anyway, but you would want to track their work. This could be a model, or a hair & make up artist for example.
You can add new users through the Users tab in the Studio Settings.