I have a windows 7, its 64 bit too.
I just reinstalled java a couple of days ago (minecraft problems) so my java is up to date.
I didnt mess with the directory i installed it too so its located in [computer - Local Disk (C:) - users - (username) - Downloads]
I run it by just opening the zip file, going into the mythruna file and running it.
Plus When I saw that didnt work i extracted it and sadly the same thing happened