Try to access http://patches.roadgrandtours.com/launcher_home.html with IE (PC) or Safari (MAC).
If the page is accessible via browser then it means something is blocking RGT Launcher from connecting to the internet.
If you have Anti-virus or a Firewall installed please white-list RGT.exe & RGT Launcher.exe.

Instructions on how to white-list can be found within the help pages of your Anti-virus or Firewall.