These actions allocate the JIRA Service Desk agent license to users and need to add users to the service-desk-agents group. This message appears when a group named service-desk-agents already exists before JIRA Service Desk is installed. Because modifying existing groups that are not created by JIRA Service Desk can have negative impacts on your system, JIRA Service Desk cannot proceed to finish the actions.
To resolve it:
Delete the existing group. JIRA Service Desk will then automatically create the service-desk-agents group.
JIRA Service Desk creates the group when you navigate to any of the following pages: the Service Desk Agents page and the Agents section on the People tab of a service desk.