Where is the OSX port for this game?
If you're asking about a 64-bit version of the Fran Bow game that runs on the newest version of the MacOS (Catalina), there isn't one right now.
The developers at Killmonday Games ARE working on a port of the game to a new game engine which will allow the game to be published for MacOS Catalina. This is not trivial to do however, and as of now, there is no expected date for the new version of Fran Bow to be published.
There are ways to run the current version of the Fran Bow game on a computer running MacOS Catalina, but they are not trivial to set up either and you may not be interested in running the game that way.
If you are still running a version of MacOS that is 32-bit, the Fran Bow game that runs on 32-bit Macs is still available under either GOG Galaxy or the Download Offline Backup Game Installers section of your GOG Library page.
Please post again if you have other questions.