Warning: this comment has little to do with the article, beyond being a rant on the approach taken by all recommendation engines I've seen. This an interesting approach, but the objective is similar to most recommendation engines: "Find me something similar to something I like". Sometimes that's a good requirement (e.g. when trying to queue up the next song in a playlist, it's good to have some similarity to the song…
What could also help in this case is "collaborative filtering", [1]. [1] https://en.wikipedia.org/wiki/Collaborative_filtering
This does make a lot more sense than analyzing the audio of the music IMO. For example youtube does this okay and if you look for a Mazzy Star song after watching Ricky and Morty (a tv show), it will recommend other Ricky and Morty soundtracks even if the style is completely different. This isn't something you can predict with just audio data.