i am on linux and haven't had to turn a file executable in 100 years, so i had to dig deep in my memory/terminal history for a minute to make this run. if anyone else has this problem, open terminal in the folder with the executable, and put "chmod +x IslandPlannerLinux.x86_64" and then it will run if you doubleclick it.
i was (genuinely) thrilled to be forced to use my brain for a minute to make this work lol
anyway tho, this is exactly what i need and i'm like "finally i don't have to be afraid of ruining everything when i play with a design" and also the way you described everything on this page is delightful. 10/10 :)