After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Drop that folder into the mods folder which is supposed to be in the game's installation folder (don't know where that is? click here)
As standardized, you must first download SuperBLT and BeardLib.
1 - Place the .dll file of SuperBLT in the PAYDAY 2 directory, with the executable.
2 - Run PAYDAY 2 as to let SuperBLT install the things it needs,
3 - And you should see a new folder, PAYDAY 2/mods
4 - Put BeardLib in the PAYDAY 2/mods folder
And you're good!
To activate the mod,
Options > Sound > Custom Heist Playlist (enable custom menu music) > Custom Heist Tracks (set music to your preferences!)