Hi, I actually came across this issue several times and decided to look into it. The problem seems to be with the .Zip compression format stripping metadata on unix systems. Tar was built as a complete archive with unix support in mind so it has better support for MacOS. I sent another dev this and after they bundled it as a .APP.TAR their game was fixed so I can confirm it works at least one case. If that does not work I also found this on unity bundling in particular. https://answers.unity.com/questions/28677/how-to-call-chmod-x-from-a-unity-mac-applications.html
If you want them all bundled as a zip this should be the fix if you can only access windows OS (although it might be easier with linux) https://stackoverflow.com/questions/434641/how-do-i-set-permissions-attributes-on-a-file-in-a-zip-file-using-pythons-zip
What I sent to the other dev {
This issue in particular is one I have seen only some people have a problem with. I downloaded several games from Itch io that didn't have this issue which made me suspect there was a workaround. I spent some time researching and it seems this is actually an issue with .zip compression. Im not a developer so I cant help too much but here is what I found. https://stackoverflow.com/questions/107903/how-to-create-a-zip-file-in-the-same-format-as-the-finders-compress-menu-item
the other solution I heard is to use .TAR https://github.com/golang/go/issues/24057
the comments on this thread are quite informative
It seems that macs default zip compression does not properly store metadata so you need to use the [ditto] command
I also found this although you probably already read it https://itch.io/docs/itch/integrating/compatibility-policy.html
I hope that helped some :)}