When you try to open “Synchronization Service” and you get an error that you are not in the group or the service is not runnning, then you need to add yourself to that admin group to be able to open the app.
- On the dirsync server, window-x and choose “Computer Management”
- Open “Local users and groups”, “Groups”, and open “ADSyncAdmins” group
- Add yourself to that group
- Sign our and sign in again.