CAP and TOT Mac downloads not working

So I ordered and downloaded Mac digital downloads of The Captive Curse and Trail of the Twister from the HER website but I'm unable to open them, the games immediately quit before anything even pops up. When I first tried opening them, a window opened saying the app "is not optimized for your Mac and needs to be updated."

I understand that Nancy Drew games can't be played on newer OS's, but my Mac OS is High Sierra Version 10.13.6; is that not compatible with the games? My Shadow at the Water's Edge still works (although in a small window) even though I'm assuming it has similar requirements to CAP and TOT. Is there anything I can do or any kind of work-around so I can play CAP and TOT? I even sent HER tech support a message but they never responded. If anyone has any ideas, your help is appreciated!