How get a sketch to run on startup of a Mac

[josephh]

This is related to :

Apps in Login Items on Mac do not launch

I am using a Macintosh When I place a Processing App in the Login Items to launch at startup, it does not launch. The App icon appears in the Dock and bounces a couple of times as though it is starting to launch, but then it disappears and the app does not launch. Can anyone explain why this doesn’t work? Thanks