Visited yesterday without charging.
These chargers have some closeup pictures on eCarUp. The description for the 5 chargers to the west says reserved for personal during working hours and public the remaining of the time. The description for the 2 chargers to the east just says "Besucher". I suppose those are also public at night, but not sure if they can also be used during the day by regular people, I guess you can always go inside and ask if the reception is open.
All chargers are accessible without any gate. Charger 1 on the west has an attached cable, the others don't.
On Chargemap we can see there used to be a different model of charger in front of the Besucher parking spots.