Not sure if all of their zips are the same, but the one for DS4.5 win64 isn't a proper zip archive, as neither winzip or winrar will touch it. I managed to open it with 7-zip only to find a 488 MB file with no file extension, I was able to extract it and then open it with 7-zip, inside this file were the installers.

The sites a clusterfuck, and their files are FUBAR, it really does make you wonder why they don't just shut everything down until they get it fixed.