FWIW, while it claims to be playable on an OG Surface, its really not.
Little in the way of touch specific controls btw
Have you tried all the workarounds that've been mentioned (Website, W10 store redeem etc etc) as I'm not seeing anyone else still with the issue that can't get round it.
When all is said and done though, this is a massive clusterfuck, we've people without codes, people who won't get them for over a week, people who ordered digital and physical copies from other places who have NO IDEA if they'll ever get a code and then at the last second the game is magically "early access" as in beta, as opposed to "early access" as in "access to it early"