The account owner can add new users at any time from the web app by navigating to Settings> Business Information > Additional Users. Click on 'New User', then select a username and password for the new user. All users share the same data in the Cavanti system, but have their own logins, individual email signatures and are scheduled and displayed separately in the calendar.
You can add as many users as you like, and a 'user' can be anything: a practitioner, a piece of equipment, or a consultation room. Just about anything that needs to be booked or scheduled in your practice can be assigned as a User, and thus show up in the calendar for all users to see.