I bought the new DLC on Steam tonight, it took about one minute to install and I cant get it to start in game. I sat around for hours waiting for it. It seems a bit odd that it would only take a minute to download from Steam so I am guessing it never installed it in the first place.
I have looked everywhere for reinstalling it and the only way I see is by buying the DLC all over again. Any idea what went wrong or where to reinstall it?

Did you activate it under the Data files tab on the launcher?

I finally got it, it was steam being dumb. I closed Steam and restarted and it started downloading the rest of my files.