Apple make it a confusing nightmare trying to download files from web servers. They assume that everything that is downloaded has to be for the iOS device in question. They can't seem to comprehend that you might be just downloading it and storing it to use on another machine elsewhere.
I went to that very page, and just couldn't make sense of the mess I was looking at while using iOS Safari. Changing to a more capable web browser, iCab, did the trick.