In some network configuration, when attempting to activate Vectorworks, you may encounter this error message:
This is primarily caused by a Proxy server or a Firewall, either locally or on your network.
However, in some instances, going to Apple > System Preferences > Network > Ethernet (Or AirPort, normally) > Advanced > Proxies and unchecking the option for "Use Passive FTP Mode (PASV)" will resolve the issue: