Unable To Upgrade Unit Factories to HQ Factories

For some reason I'm unable to build/upgrade any of my unit factories the an HQ Factory. I'm currently playing the Steam version of SC:FA 1.6.6., But there is no option on the lower left of the Factory build menu to upgrade it to an HQ. Am I missing something? Is there a specific process you need to go through for that HQ upgrade option to pop up? Is it part of a mod or a newer version/patch of the game?? If anyone can help please comment back, thanks!

Umm, play on FAF? Not on steam?
The vanilla game doesn't have the HQ system as it was added in FAF so it makes sense it's not on steam.

Ok, so another stupid question haha! Where can I find/download the version of the game I need that includes HQ Factories? or is it just a Mod? Anyone have a link?

I've been playing SC:FA since it came out, but I'm brand new to the FAF site/community, so still learning how to navigate the site.

faforever.com, download client, set up games through the client.

K I'll give that a try, Thank you!!