The issue is that the binary file inside the .app is not marked as executable. macOS apps are actually specially organized folders which contain a main executable, and the rest of the supporting files, + a manifest.
For whatever reason, the binary inside the app is not marked as executable, which means macOS tries to open the app, but can't find any file to execute.
I was able to get it to launch by using terminal and running chmod +x "[path to .app file]/lilLadds.app/Contents/MacOS/lilLadds" and then doing right-click ➜ Shift+Open on the .app file to enable the "Open" option on the "Unverified Developer" screen.
(chmod is a command-line utility to change file attributes. +x is telling it to add (+) the executable attribute, which tells macOS that it is a binary executable.)