Alda seems greatly inspired by the syntax of LilyPond, and in fact, I actually think the musical rendering is done via LilyPond. I'm surprised the docs don't seem to mention this heritage at all.
You can hear some recordings presumably made with these programs on this release: https://www.discogs.com/Various-Music-From-Mathematics/relea...
Some of it is gimmicky, some still kinda rocks.
The problem I've always had with the language is that it's quite arcane and if you want to do anything weird (like, a tie to nowhere) you're either at the mercy of somebody else having solved the problem first, or failing that, a huge learning curve. It's a lot like latex in that way. That said, if you just need to do simple stuff, the language almost magically gets out of your way.
It has a `lilypond` formula that has worked fine for me. Beware though that it installs some kind of TeX repository sized 7 GB.
Sorry I can't be of more help immediately!