Here in this folder you will add the .ogg file. You can create a .ogg file by converting a mp3 file
to .ogg format.

Rename your files in relation to what song you would like to work with certain parts of a heist.
I would recommend rename your .ogg files to these.

stealth.ogg = Stealth Gameplay
assault.ogg = When an assault begins
buildup.ogg = Just before an assault begins
control.ogg = The track in between assault phases  



Youtube to mp3: https://www.easymp3converter.com/

Mp3 to .ogg converter: https://www.onlineconverter.com/mp3-to-ogg