Game does not show up after redeemed key.

When you are on the connect site, there should be tabs on the left. When you see the product key tab show up, you should have a product key right there. If one is not showing up, there is a link to "request new product key".

After you redeem the code, it will probably take a few days before you get the update itself, and access to the private feedback forums.

I redeemed the code probably within 15 minutes of when it was posted. I can't explain why your keys didn't show up if the message you are getting says that code has already been redeemed. Weird... Did you check to see if your key quantity went up?

You should have received a product key after signing up for the beta. You need to use this product key if you have not already and redeem it on the dashboard to download the app.

It was a PC/Xbox One key which I assume works for both. When I opened the Companion app I could only find the 'redeem code' button under the Xbox tab however. There was no redeem key button in the Windows tab, but I read somewhere that if you own the game
you can access it across all platforms so I redeemed it in the Xbox tab. Does this mess things up?

This key is not redeemed on Xbox.com. This is your product key. Load the game up and when you log in, it should ask you to input the key at that time from within the game.