I tried opening the .rar file in that second link with 7-Zip and it seemed to work fine. I also extracted it, no errors. (Haven't tried the mods).
Maybe the file got corrupted while you were downloading it, so you can try downloading it again.
Another possible cause can be that you're trying to open it while it is in a protected directory, and 7-Zip doesn't have the necessary requirements, though this is most unlikely to be it.
By the way, i'm a Windows user, so i may not be very helpful at all if you're using another OS.
EDIT: I forgot to mention the possibility that the file got corrupted from the start and the author hasn't noticed. If the problem persists, maybe you can stay for updates from the author, or try to kindly request help on the matter.