Hello Marco_duerst
Navigating through the Spotify database only on the radio display is not possible.
Spotify Connect only uses the radio as a speaker, so to speak, and you cannot search for a track on the radio or anything similar. However, if a playlist is playing, you can select play/pause, forward and back within the playlist on the radio (or the remote control). In addition, a Spotify playlist can be saved as a favourite in the same way as radio stations, which can then only be started from the radio.
Greetings
Andy from Hama