1) Download the game normaly with your GF client.
2) DO NOT INSTALL the game from the GF client.
3) Find the setup file you just downloaded on your computer.
(for me this is Documents>GameFly>downloads>60671435)(Each game you download will get its own number just find the numbered file for IRG)
4) Right click Imperium Romanum Gold_v1.04.147_ddsetup(Choose Properties)
5) Under the Compatibility tab check the box marked "Run this program in compatibility mode for: and select Windows XP (Service Pack 2)
6) Press Apply on the bottom right of the window and close it.
7) Double click Imperium Romanum Gold_v1.04.147_ddsetup (This will start the install of the game, finish the install as normal.)