The management role "{0}" can't be assigned to the role assignment policy because it isn't an end-user role. Only end-user ...

The management role "{0}" can't be assigned to the role assignment policy because it isn't an end-user role. Only end-user roles can be assigned to assignment policies. To find out which management roles are end-user roles, use the Get-ManagementRole cmdlet and check the IsEndUserRole property of returned roles.