Hi @TL_10544753.
I think with an Enterprise package, users are unlimited. In Composer, you can validate by navigating to Monitoring > Subsystems > LicensingSubsystemSettings to review your license features. If the twx_named_user has a Total Feature Count and Available Feature Count of uncounted, you have unlimited users.
In regard to the Administrator account, there is no limit on the number of concurrent logins. However, best practices dictate that you should not use this account for normal daily activities. For security reasons such as tracking and accountability, you should create unique user accounts and add those with a need to the Administrators group.
You'll have to be more specific regarding user group limitations and anything else I may have misunderstood from your post.
Regards.
--Sharon