When running Negative Lab Pro on macOS Catalina, you will encounter a troubling error about “magick” not being signed and the only options available are “Move to Trash” or “Cancel”.
DO NOT “Move to Trash”. Instead press “Cancel”.
Then, open System Preferences -> Security & Privacy. At the bottom it should say that the system recently tried to open “magick” with some other information. There should be a button that says “Open Anyway”. Click it.
Try running Negative Lab Pro again, and you will get similar messages for various “.dylib” files. You will need to repeat the above for these as well.
Once all of the files have been approved to be opened by you, Negative Lab Pro should work as expected.
I think the developer should get signed versions of these programs and libraries, but in the meantime I hope this helps someone.