Visited yesterday without charging.
The chargers are in the private parking lot for the "Schule für Gestaltung".
A sign says the parking spots 10 to 24 are paid between 08h and 17h during the week and that parking cards can be obtained at the reception.
No idea whether the chargers would be open to visitors outside of work hours.
There are 4 stations, but only 3 of them are visible in the eCarUp app, IchTankeStrom and other roaming apps. The missing station number 2 has a working QR code though, and I suppose if you connect an RFID tag to your eCarUp account you will be able to charge here.