Occasionally, when you download a zipped app on macOS, it refuses to open, displaying an annoying message like the following:
The vast majority of the time, there's nothing actually wrong with the program. A re-download or checksum verification never hurts, but in my experience, this is usually a glitch caused by an over-zealous Gatekeeper.
The solution is simple: just make a copy of the affected app without preserving certain metadata:
cp -RX /path/to/supposedly/damaged/program.app /path/to/fixed/program.app
Or, use the 5-line applet I uploaded here for your convenience.
Hope that helps!