Gamemusic is usually made as assignment for a game, not the other way around. It does happen, but its occasion is rare.
Usually with gameprojects, the plan is already made about the game, so the choice in music is not that hard to make for the designer. Often the mucisian is being shown some of the game so the music can match the feelings of the game very well. When the music doesn't match that well, a game usually turns out bad or the music is abandoned even.
The only way you can still make use of the music, is by sharing it so others might listen to it and then get inspired to change the game to fit your level.
In case of this forum, the music could also be featured in a Knytt Stories Level. Even then, you'll first have to share the music, so people who're interested can listen to it and then get ideas for a Knytt Stories level.