Minute 1 to 3: list your scenes
Title screen, main level or two, a menu, credits. That is usually four to six tracks.
Minute 4 to 8: fill the slots
Open the Soundtrack Builder, press Auto-fill, then swap any track that does not fit by pressing Change and previewing options. Everything is saved in your browser.
Minute 9: export
Copy CREDITS.txt into your credits screen and your submission page. Download the MP3s.
Minute 10: wire it up
Drop the MP3s in your project. The Engines page has short examples for Godot, Unity, Phaser and plain HTML. Use a crossfade between tracks rather than looping one song.
Keep the file small
Jam sites often limit upload size. A four-minute MP3 is about 4 to 6 MB, so five tracks are around 25 MB. Cut the list or trim tracks if you need to.
Quick answers
Is jam music allowed to be pre-made?
Rules vary by jam. Most allow pre-made assets if they are credited and the licence allows it. Check your jam page.
Try it
Open the Soundtrack Builder and give each scene a track, or browse the zones on the map.