Visited yesterday without charging.
I'm not really sure what their concept is. There's a sign "P & charge" at the entrance and a large sign explaining how to start a charge, but there's no mention of opening hours or which spots to use. Chargers 1 & 2 are labelled "Besucher" on location, and named "Sablux AG" on eCarUp. All other spots are labelled "Streit AG" both on location and in the app.
At the very least I guess it's fine to use any charger outside of business hours.
The large explanation sign mentions chargers 1 to 4, but makes no mention of the other chargers. More chargers appeared gradually in the live data, so it's possible that sign was made when there were just 4 total chargers.
The road that gives access to this business is currently under construction work and it's temporarily a one-way street. You have to access from the south.