NightWing wrote: Click the link (below the button at the left) to play the song online. Does it play?

This is a Samsung Android tablet.

Android recognises that file as an audio file and offers to play it in one on the three music apps I have:
- Spotify - I installed it, won't play it - says it doesn't have the song
- VLC - I installed it, won't play it (no codec - there isn't one for Android I think)
- YouTube Music - I didn't install it - plays fine

I could set Android to play 'files of that type' in YouTube Music automatically in future - though I don't. Most people would.

[All of that happens with Joe's 'longestsong.mid' file too. It's theplaying within Microsoft Onedrive that appears to work but doesn't. It presumably recognises it's music but lacks a codec.]

Midi support is not 'built into' Android but opening correctly-described files in an app is, and a music player is often installed by default. So it might work, and might not.

[Linux is similar, except its file-type detection is more sophisticated. Android uses file-extensions like Windows, Linux mime-types.]

Opening .abc files in Android in a text editor can be a problem, btw, because they are not recocnised as text files.