I extracted it to a folder and copied the image, changes, and sources files from inside the package to that same folder. I dragged the image onto the app. Squeak opened. I opened a Transcript and saved and quit the image.
I start the image from the command line with a startup script file which just prints something to the command line:
./Squeak6.0alpha-21736-64bit.app/Contents/MacOS/Squeak Squeak6.0alpha-21736-64bit.image latest.st
The file latest.st is in the same folder and just contains this:
Transcript cr; show: 'execute latest.st‘
Instead of printing to the Transcript a notifier with the following error message opens:
Cannot start a second instance of Squeak\with the image „latest.st“ because the VM is configured as singleton application.
http://lists.squeakfoundation.org/pipermail/squeak-dev/2022-May/220459.html