Visited on October 26 without charging.
Based on the name I expected this would be a business park, but it seems to be just a residential complex.
The entrance is on the small street starting just below the bus stop. On OpenStreetMap this street is unnamed, on Google Maps it has the same name as he main road, Schlossstrasse. The sign at the beginning of the road says "Schlossstrasse Nr.26-164".
At the end of this cul-de-sac there's a sign "Besucher" pointing to one side where there are about 10 covered parking spaces. The charger is among those parking spaces without any special signage.
There are Google Street View images from August 2021 until the end of the road. We see there's no charger yet on those pictures.