If a Group ist imported from Active Directory the Members tab on the Group ist not available.
http://enterprise.arcgis.com/en/portal/latest/administer/windows/manage-groups.htm#ESRI_SECTION1_123...
how is it then possible to assign die Group role 'Group Manager' or is this not possible?
If a group ist created with the option 'Who can contribute content to the group: Only group owner and Managers' will there only the Group Owner be able to add Content to the Group?