I'm not super familiar with GeneCompare, but maybe you are lucky. Some installation EXE files are really just self-extracting zip files. I'd try and see if you can open and extract it by hand with something like 7zip.
It is a self-extracting .zip.
Gave it a crack with winRAR and no problems. In hindsight, it was pretty obvious. Thanks!!
To clarify, by the extractor to install the dll files, you mean the functional developer library mentioned in the readme?
I have W10 and it works just fine for me, but unfortunately I installed it years ago so I can't say anything specific about installing it. When I tried running the functional developer library installer again just now, it worked just fine. Have you tried running it as an admin already? Checked if your security settings may be blocking it from running properly?
Creatures wiki also suggests Gendiff, though that requires you to be comfortable using a command line, and Norns of the Round Table has a Python tool built off of it.
The one in the readme, correct.
I tried using permissions and compatability mode, but neither helped. I think it's because my copy of winZIP has stopped giving me freebies. WinRAR seems to do the trick.
I've used simple command lines before so I think I can use this. I'll have to play around and see which works best for me.