I'm not quite sure where you're having issues at the moment, are you on Windows?
If so, you extract it the same way you do with Grove since it's the same engine, just 'right-click', then select the option closest to 'Extract to new folder / "ProwlerDemo v0.11 WINDOWS"'.
Also let me know if you're attempting to run it off of the launcher. It might be best to try downloading it from the website version of itch.io then doing the extract if you're having issues with that.
- RegalBuster