It's a false positive by the anti-virus software. Just tell him to tell the anti-virus software to ignore the false flag and run it. It's more of an issue with the anti-virus software rather than the app itself.

You can try to uncheck "compress the runtime" in the application properties to see if that works. Otherwise for a commercial game that you're selling, if it's worth the hassle and money you can try to "sign your application" as the instructions from the link I posted. Doesn't seem to be worth it though due to the hassle. Might as well just add a disclaimer about a possibility of a virus false positive when people try and download the game. this is by u/Sumo148