Can't install Joplin on MacOS - Help!

MacOS Catalina

On opening the package I get this warning:

"Joplin” can’t be opened because Apple cannot check it for malicious software.
This software needs to be updated. Contact the developer for more information.

Maybe this is helpful?
Safely open apps on your Mac - Apple Support (via Apple can’t check app for malicious software - Apple Support)

This thread on this forum may help explain what’s happening.