Problem opening stand alone game

Hello, I sent my new project to a friend. He has Windows and Mac so I sent both forms of the stand alone game. He said he couldn’t open either. With the Mac he got this message: “The application “RPG Test” can’t be opened.” He said that is all it said and didn’t explain why. His operating system is 10.15.6. Any ideas on how he can get the game to open?

On Windows, maybe he got a blue security warning. There’s a sentence to click on that screen to show a new button to run the game anyway.
No idea about mac.