I've recently been trying to get Rainbow Six: Siege to work, but I get the flickering issue, that I should be able to fix by updating to the crimson drivers, but I can't seem to find any download for Windows 8, AMD seem to support Windows 7, Windows 8.1 and Windows 10 but not Windows 8. I've tried downloading the 8.1 version to see if that would do, but it wouldn't install of course.
So now I'm thinking because of this I'll probably have to just refund the game. Is there really no support for Windows 8 anymore?
There are no new drivers for Windows 8.
Microsoft is offering free upgrades to Windows 10, so I would suggest you take advantage of the upgrade offer.