Sound Emitters. Study this map, music plays near the village. https://www.beamng.com/resources/the-stairway-mountain.207/
Thank you! I was able to get it to work, I guess my problem was the folder name because if the file is in any folder that isn't named correctly the game just straight up crashes when you set the music.
I posted a video on how to convert wav/mp4/ect to the OGG format. Its pretty easy to take a video capture of anything on youtube and upload the video from you screenshot folder. upload to a converter website and download just the audio in OGG format. I don't know what program normally converts to OGG and the website limits you to about 200 megs at a time. (43 sec or so for me)