Hi @Odyk25, you can add this campaign by subscribing to it, which auto-downloads it. Then you can find it in-game in the drop-down menu in the campaigns section (the same place you can find the base game campaigns like Fall of the Trident).

where do I download the audio files?

Hi @Lerry2, what audio files do you mean? All of the audio and music that I use for this campaign comes from the base game.