A single registry entry enables the Quest add-on for the Origin version. All the game files needed are already included with the Origin downloaded, and they're not offering it as DLC, so it makes me think this was just an oversight. I've shared it with them and we'll see if they include it as an update, but for now:
x64
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Westwood\Nox]
"SKU"=dword:00002500
x86
[HKEY_LOCAL_MACHINE\SOFTWARE\Westwood\Nox]
"SKU"=dword:00002500