There is no limit to how many users and admins you can create, albeit within the number of people you can store, which varies depending on the plan. But again, this is a limit of active people profiles, which does not imply limitss related to role. All people with an active profile can be made users, admins, or be assigned any other role.
Anyone and everyone with an active profile recorded under the People section can become a user, by creating a user account for them.
Any user can be made an admin, too. ChMeetings does not limit the number of admins you can have with a specific plan. If you want to make everyone an admin, you can.
Note: Active people are those listed under your People section and do not include profiles in deleted or archived people reports. Learn more.