Can’t run it in macOS Mojave 10.14.6 (Early 2015). :(
Sounds like an amazing tool, thought.
Unfortunately OSX gatekeeper causes lots of problems distributing free software. If you have the gatekeeper turned off and do the right click > open thing and still have issues, then I'm not sure whats wrong. You could try downloading the love2d app from https://love2d.org/, then grab the .love file from picosync.app/Contents/Resources/picosync.love and drag and drop it onto the love2d app.