With the IUM free license, the full range of functions is available to you. Except for the restriction to 5 users / shared licenses and one group pair, the normal setup for IUM can be used in Confluence.
Limitations
IUM Group Settings
Licenses reserved for API request is set to 3
With shared license only the values 1-5 can be set.
IUM User Management
A maximum of 5 users can be added to the ium user group.
IUM Automatic User Sync Job
A maximum of 5 users will be synchronized into the ium user group (make sure that the original group does not contain more than 5 users in total).
Popup message (only for admins)
The ium user group is regularly checked and, if necessary, users are removed (max 5 users are allowed in ium4confluence free). In this case, the admin receives a pop-up notification.