Is this on a personal or work computer? It may be that your work network is blocking the site because it conflicts with company security methods. If it is a personal computer, it may be possible that it’s a bad link or the hosting site may be down or experiencing issues. I assume the install pretty much finished and it’s failing on the process that tries to access their server for the most current database for virus definitions. Try again later or post the link (if using one) you are try connect to the server with.