itch.io

Sorry to hear that. Do you have the problem with other programs as well or just this one? Sadly I don't know anything about Mac and I don't have the possibility to test the Mac build myself. 

But I found this video that deals with a similar problem in an RPG Maker game. Visual Novel Maker and RPG Maker are from the same developer, so maybe this solution will help.

YouTube

go into mac terminal copy and paste this ( chmod -R 777 ) then drag and drop the game into terminal and hit enter.