“unable to load java Runtime environment”
Can you run the current Processing app that is from the Processing.org website? It relies upon Java 17 so you need that on your system. Another thing that you can try is to right-click on the app and go to Contents/MacOS. The executable in there should launch when you double click on it. For whatever it’s worth I can’t run the DropBox version on my system either but I get a different error telling me the developer can’t be verified; likely a gatekeeper error. You may have to resort to re-compiling your own copy of the current editor. It’s not that difficult once you have all the requisite files.