Could you please post the site link you are downloading the mod from? And what system are you using? (Ex: Windows 7)
I use Windows 8/8.1 and I downloaded it perfectly fine. It should pop up at the bottom a yellow and white box (if you have Windows 8, not sure about Windows 7) and it should have "Open, save, and cancel" options. Mine downloaded nice and slow. The mod works perfectly fine.
Maybe Mediafire at the time isn't working. Websites don't always work perfectly. And how "Download" button are you clicking?