Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/OpenAudio_ArduinoLibrary/src/commit/9bd938f20c68c0168727dfec8bcaa57ac84e4f00/examples/ReceiverPart2
You should set ROOT_URL correctly, otherwise the web may not work correctly.