You need your HFBK Self-Service account to connect to Eduroam. What is Self-Service ("Eigenservice")?
Follow the instructions for your corresponding devices on the DFN website:
Linux
The DFN also offers further up-to-date help for setting up:
https://doku.tid.dfn.de/de:eduroam:easyroam-anleitungen
https://doku.tid.dfn.de/de:eduroam:easyroam-anleitungen