A user can have multiple companies associated to their account, bear in mind each company has its own separate billing account.
The billing amount depends on the number of users within the company. If the company contains 3 users, you will be billed for 3 users.
Users who are associated with a paid company account will have all pro abilities within the company. I.e. sharing restrictions and data storage restrictions no longer apply, regardless if said user is on a free account themselves.
