Premiere Plugin Location is at C:\Program Files\Adobe\Common\Plug-Ins\7.0\Mediacore\
When you run the installer you can Browse to your desktop let the installer install the folder and then manually move it to the Premiere Plugin Location.
It seems when you first run the installer it acts as an uninstaller before installing, I wonder if there is some weird bug there.
Thanks Jamie!
I've actually found the issue, Digital Anarchy pointed it out. The Effect was disabled for some reason. So I have renabled it the Effects window, this is from them:
The effect probably got disabled in Premiere. Click the menu at the top of the Effects panel (the 3 horizontal lines) and select Manage Video Effects. You should see Flicker Free here -- check the Enabled box next to it to re-enable it.
It seems to be working now, but I'm unsure why it was disabled in the first place.