The mod system is based around having the program change the text of the game scripts, but for MacOS all the game files including the scripts are packed inside the .pck file so the mod system is not able to function. For the basic solution see this topic(an earlier version is available in the Help section of the mod menu): https://itch.io/t/628179/how-to-make-mods-work-on-mac-osx-without-wine
Also, recently we've had a case where that guide appeared to not work as expected due to changes in the Godot Engine. If you find that to be the case, then I recommend using this older Mac folder instead: https://mega.nz/file/3MJQVJ4Y#w1vLnCqyJ8v9AMdiRLz1lf5ZJHGW9dyNgFaMdp5hIb0 (if it asks for the encryption key, it's the portion of the link after the #)