MSP comes with administrator installations for 4 computers. (Please note this is based on the number of computers, not number of people. Someone with two computers counts as two installations.) Additional computer installations can be purchased for a one time fee of $15 plus an additional $6 per month. You can also allow people to access the program as Web Admins. Web Admins will not be able to do everything that is available in the desktop software, but can make manual changes to schedules, add, delete, or edit volunteer profiles, send emails to volunteers, and more.
If you have the Plus Edition, you can also allow people to access the program as Leaders. These individuals have different privileges than a installation administrator or a Web Admin, but can do some manual scheduling, send emails to volunteers, and edit volunteer profiles.
For more information on the difference between administrators and Leaders, see this article: