Author here. The zip shouldn't need to be saved in any special format. If WinRAR is posing problems then please file an issue because I'd like to fix that. That error doesn't seem like something that would indicate executable corruption. I want to learn more.

Have to say though, using zip so you can reuse the compression is quite a masterstroke.

I tried to add a file using Windows file explorer, but it just complains "The Compressed (zipped) Folder is invalid or corrupted."

This is on Windows 10 19042 build.

7-Zip doesn't even see the folders for that matter.

IDK if this is enough

https://pastebin.com/8RyPWQFf

Sure thing, will provide as much info as possible.