Yesterday I called with an Microfocus-Employee, and they give me the fix to my issue. The way is the same like GW Mobility, only the path is a little different.

-> copie the GW-SOAP certificate (in .pem-format) to /var/lib/datasync/connectors/groupwise/ and then restart the Datasync

They told me too, that at this Time there is no MicroFocus-Product, wich can sync the calender from Vibe to GroupWise, but they will talk to the Microfocus productmanagment for this probleme

for me the thread can be closed