Question on number of users for Pro

Hi there.  I'm trying to understand which plan makes the most sense.

We are a small company and are looking to give 3 employees the ability to have access to 1 host computer (our shared server) so they can access these shared files from home.  Could I just get one individual plan and allow those 3 employees to have remote access to the 1 host computer?  Or would I need 3 individual plans to allow those users access to the computer?  Also, can 3 users have simultaneous access to one host computer at a time?

(If I do need more than one individual plan, then the power users plan seems more cost-effective).

Thanks for the help!