Hi wallach! Thanks a lot for letting us know and describing the issue in detail : ) We've had this problem before (we believe it was you who told us about it, actually!) and thought we dealt with it, but you're probably right and our solution didn't withstand the test of client update. We know what to do to fix it more, er, permanently, though, so thanks again for bringing it to our attention!
Hey there, I took a look at the issue and it seems v23 of the app isn't able to extract the .rar (for the Windows build) as it is currently.
The good news is that the next version of the app (v25) installs it correctly. If you wait long enough, the problem will resolve itself ;) However I'd recommend using butler to push the windows build of the game instead, you can find more information here: https://itch.io/docs/itch/integrating/quickstart.html