Hey, so I downloaded the Dragonborn DLC today, but when I get on the game and try to play it never starts. I've been fast traveling to pretty much everywhere in the game constantly for around 3 hours, and the cultists just never come to me. Also, there doesn't seem to be any new boat or NPC in the Windhelm docks area, as far as I can tell the game doesn't know that I've downloaded the DLC. Dragonborn is included in my list of add-ons at the startup screen, I'm getting super frustrated and it just won't start. Please help.

Have you tried re-downloading and installing the dlc?

Yes...

Have you updates your game with the 1.8 patch needed before you download the DLC.