Did a few searches and found other people who had the same problem, but didn't find any real solution.
The game is Terra Cresta 3D. But it doesn't really matter, because most of the isos I try dont have working music. And I also get the Fatal Error during gameplay, which is presumably when a new music track is supposed to be loaded.
The filename of the iso:
Terra Cresta 3D (Saturn) T01 Mode1 2048
iso mounted with Daemon Tools.
The files are all in .wav format and play just fine in any media player.
So what can I do here?
UPDATE: I just tried mounting the cue instead of the iso, and now I have music. But another thing: Many games I try out, when I mount the cue in Daemon, it gives me an error and wont mount the cue. So then I can't play the game at all, much less without music.
UPDATE 2: Tried a different game and sure enough when I tried to mount the cue it gave me an error. So I converted all the files to 44100 Hz .WAV and then it mounted and the game runs perfectly. So I think I may have solved my Saturn emu problems, lol.