Help, I'm lost!

So I went to the main page (horizonmb) to download the horizon program. Every time I try to download and install it, it gives me the program jdownload. What’s going on?
I’m trying to download the Stampy Cat map from youtube to my xbox 360 for my son.

When you run the installer, be sure to decline to everything except the actual download for Horizon.
Here’s the direct link if you’d like to use that: