Something is up with your install.sh script … maybe the js is referencing the wrong location / file? Certainly not the latest version.
When I run „Reinstall Spotify Connect Service“ from the web interface it installs
-rwxrwxrwx 1 root root 13707640 Mar 5 16:08 librespot
When I download the spotifyconnect.tar file (http://shop.max2play.com/media/downloadable/beta/spotifyconnect.tar) and run the install.sh in it as root it installs this version
-rwxrwxrwx 1 root root 14617892 May 7 10:50 librespot
which works 🙂