Visited on October 12 without charging.
The area is accessible without any gate. On the wall there's a sign repeating the information visible in the eCarUp description: the chargers are reserved for employees during work hours, but otherwise open to the public. There's a difference in the exact hours, the app says 7-17, while the wall says 6-18.
There's a QR code on each station. The one on the left station is very faded and I was not able to read it. The other 2 QR codes match with the chargers named "Mitte" and "Rechts" on eCarUp, so the physical order seems to match the description.