From what I understand they downloaded the whole game when it was in v0.13.2 and the patch framework was introduced.
Then they applied the patch to get it to v0.14 and it worked fine (so unless there's a difference between a patched v0.14 and a fresh one it should be fine to apply the v0.15 patch on top of it).
Finally comes the time to install the v0.15 patch and it doesn't work anymore. I can confirm that happens, Ren'Py gives an error.
The whole v0.15 download works though so I'm not sure what's wrong with the patch files (other than having a non-executable Harem_Hotel.sh, but that's easily fixed).