Spotifeed has been discontinued.
Unfortunately, Spotify has made critical changes to their podcast download infrastructure that prevents Spotifeed from working. While Spotifeed can still access the show and episode data, the audio file downloads are no longer accessible. He's dead, Jim.
The technical details: Spotify's anon-podcast.scdn.co server has been discontinued. This served as an unauthenticated proxy server for podcast episode audio. They have switched to streaming directly from the podcast's source server. For non-exclusive podcasts, that is simply whatever is in the RSS feed (in which case, you can access those podcasts directly without Spotifeed's help). For exclusive podcasts, Spotify is using their audio-fa.scdn.co server, which appears to be using a chunked MP4 stream that is not usable by general podcast clients. That means Spotifeed would have to re-host the podcast audio files to make those downloadable, which is not feasible or legal.
The source code to this site is available on GitHub