Are you actually having downloading issues? The DLC is fine for Macs so no issue with that. Did you double check your Downloads to see if it’s in there? It should be titled ‘14nightswithyou-free’ if you need to search for it.
If you do have this file, are your issues actually with getting the DLC to work? In that case, you have to manually install the DLC to the game in order to play it.