AFAIK, the Downloads button/link on the hotbar at the top is broken. I've tried clicking on it with IE, Firefox, Chrome, and on two seperate computers, each using a different ISP, and it's completely and thoroughly BROKEN. If there is another place to click on Downloads that actually works, I'm not noticing it.
Yes, the link on the main page is broken. It refers to http://www.lcpdfr.com/files/ which generates a "This page can't be displayed" message by browsers. I believe the link needs to be updated, so that it points to http://www.lcpdfr.com/downloads/gta5mods/