PLEASE NOTE: after downloading the DLC you will find the "Soundtrack" folder with the audio files in your game folder (usually C:/Program Files (x86)/Steam/steamapps/common/In Verbis Virtus).
You can also access the folder from Steam library -> In Verbis Virtus -> Play -> Open Soundtrack folder
Official In Verbis Virtus soundtrack by Gianmarco Leone. (MP3 320Kbps and FLAC formats)