I could make a guess at the reason, but I'm trying to be nicer these days.

If you go to this page:
http://www.mapfiend.net/index.php?pageid=mappacks

Click the all maps radial button and then the download maps button, what happens?

When I do it, I get the download pop up and I download the file.

Maybe the security settings in your browser are blocking this? Are you able to download anything on that page?