While trying to install Plastic SCM on a MacOS machine you get the following error message:
Apple has adopted a new security policy where installers not signed are potentially considered malicious software. We are working to have it solved soon.
If you right click on the installer and select Open, you should be presented with the same dialog box but with an option to open the installer.
Alternatively, you should be able to approve our software by going to the MacOS preferences panel. For more information, please see here.