Earlier quoted context omitted.
Can you share details of what you're seeing? If you want to send it to me directly you can email me as rod at fatpick.
This is what I get: https://imgur.com/a/aHy0c0Z Would love to try it!
Are you seeing that problem when opening the DMG or the app itself? Does it help to use the right-click-and-choose-open approach?
For what it is worth you can download (a zipped version of) the .app file directly from https://www.fatpick.com/releases/FATpick-1.3.5-mac.zip, if that would work around the problem.