edit: as seen in the author's reply below, this issue has been fixed. Game installs correctly in the itch.io app under Linux now.
tiny bug report: I was forced to play it in the browser though as installing via the itch.io app gave me a "no executable found" on Ubuntu. I am guessing because itch.io doesn't understand deb files. Check out the following documentation for that. https://itch.io/docs/itch/integrating/platforms/linux.html