did you look in the directory to see what is there?
Kind of, there is a CentOS-7-x86_64-GenericCloud.raw.tar.gz ( compare with CentOS-7-x86_64-GenericCloud.raw.xz )
But again link is not good, and why put raw disk inside the tar? It would me more natural to have compressed image so one can do {z,bz,xc}cat cloud.raw.xz > /dev/lvm/vm-disk for example.
Official wiki link is broken regardless.