History Channel & Apple TV

I recently purchased an Apple TV and was excited to see that the History Channel was an available app. I went through the process of setting up the app, (choosing COX as my provider, entering the Apple TV code, etc.) and was successful at doing so. When I went to watch Vikings however, I was told that I needed to pay for it. Is this accurate? Why would I need to pay Apple to watch Vikings if I already confirmed I have that channel with COX?