Failed to sign in: A connection with the server could not be established. Check that the computer is connected to the internet and that no firewall is blocking this program.

In order to fix this error you need to do the following:

1) Check if the TLS 1.0, 1.1, and 1.2 options are enabled in your browser settings (Control panel — Internet options — Advanced tab). If not, check mark them (usually works with Opera and IE browsers).
2) In the same settings, try disabling the "Warn about certificate address mismatch "," Warn to switch security mode" and "Warn if publishing redirected ".
Download the executive file again and repeat the installation.