Project's README says:

Also requires a spotify premium account, and the spotify_appkey.key (the binary version) file needs to be obtained from https://developer.spotify.com/my-account/keys , and needs to placed in the python scripts directory, or have the path specified with the -k parameter

According to Spotify's web, key generation and retrieval service has been deprecated:

The libspotify key generation and retrieval service has been deprecated, along with libspotify.
You may apply to get a key using our App-key Request Form for private, individual usage. Bear in mind that you should do no new development using libspotify.

Is it possible to make the current version of spotify-connect-web work with the new app-key system?

Anyhow, README should be updated to reflect these changes.
Thanks!!!