While running grbgetkey to retrieve a license file, you might receive the error:
Communication failed, check your network connection or set variable HTTPS_PROXY if you need a proxy
If your computer is connected to the internet but requires a proxy, you can specify a username and password in the environment variables HTTPS_PROXY and HTTP_PROXY by setting them to http://username:password@proxy-server:port.
For further details on resolving this error, please see How do I resolve the error "Communication failed" from grbgetkey?