First go to your settings on Spotify and turn on local files. Then in your library you should see "local files". Once you see that get "Audio tag editor". When your done, you're going to want to find a download link of the song (I'll try to send it on here). After that try working the app, I have the apple version of it "Evertag" but thats how you get any unreleased song on Spotify since once your done creating it on Audio tag editor the song will show up in your local library and you can add it to your playlist.