1. Make sure you have an OPUS media player installed. If not, you can get a free player vlc from here:
https://www.videolan.org/index.html

2. Navigate into where the game is downloaded. Easy way is to right click the game in your library and click Browse Local Files.

3. Go into the folder in this order:
game
music

4. You will find a bunch of opus files. This is a lossless audio music format. Go ahead and enjoy!