Hey there,
I bought the Limited edition of Halo 5 and every time I enter my digital content code for the REQ packs and Fall of Reach series I get “We couldn’t find your code” error. Can I get a new code or what can be done?
I know this sounds silly but read the code VERY CAREFULLY. I saw another thread in here where someone had a similar problem, and it turned out due to some poor printing he had mistaken a Q for an O.
I just tried that, the code I got in my box was pretty damaged and some of the letters are hard to make out. I’ve tried at least 30 different possible variations to no avail 
I’d contact Xbox support then, see what they can do. Most of the responses you will receive here will be from other players, and not necessarily people that can do anything for you directly.
soooo how do I put in the req code