Visited on October 23 and did a short charge with eCarUp app.
The chargers are in the underground parking. There's no gate, spots 09+10 have signs "nur für Elektrofahrzeuge" with electric pump symbol. There are 2 more stations on the back of the eCarUp stations among private parking spaces. Only the 2 public stations have QR codes.
The parking has very little signage. Outside there's just a "P" symbol with an arrow, and below a little green sign saying "Ladestation im Parkalle". Nowhere does it say the parking is reserved for customers. Nowhere does it say a closing time or park time limit. I couldn't find any parking meter, it seems to be free.
The underground parking is very small. There are only about 10 spaces open to the "public", the others are all private. Presumably it's intended for customers of Denner and the cafe. In the parking there's a door with big "Denner" sign which presumably leads directly to the store, but I didn't try it. There are about as many parking spaces outside.
There's a weird live data behavior. Every day at 4 in the morning, the chargers seem to reset. The stations then occasionally show out of service for a while until it switches back to available. This seems to be mostly a problem with charger 09 where it happens most days. It's probably just an internet connectivity issue, but it means without having an RFID connected to your eCarUp account it might not be possible to charge. While I was there both chargers were shown available, otherwise I would have tried to get a session started on 09.