Trying to get the polish dub DLC, since I dislike the english voice actors.

where exactly do I find the redemption code it requires?

You don't need a code, just select the DLC and click the Download button that appears below the Redeem code field. The code is for some other DLC that can be unlocked if you bought the game from some specific vendor, or some such.

Ahhh, thanks lad, my bad.