Get "Unable to connect to world" with Advanced Dragons 2

I bought the Advanced Dragons 2 world pack however it would not let me use it or create a world using it. It started with it saying "unable to connect to world. Please check your internet connection." But I'm certain my internet and NAT type is not the issue. Now when I attempt to make a world using the Advanced Dragons 2 pack, it doesn't even let me select settings or anything. In fact, it doesn't let me do anything.