So I played Halo mcc between the dates that were given for the free Odst game and nameplates. However for some reason the Odst campaign is not free to me I did get the nameplates that were given to players who played between the dates but no odst campaign why 343.
They are rolling out the codes, yours may just be at the end of the rollout. I got my free month of XBL later than most people did, so this might be a similar thing. Patience, young TERMINATOR333 
Did your specific gamertag meet the following circumstances?
> Online users that logged in with their Xbox Live account and played Halo: The Master Chief Collection on any day from November 11, 2014 through December 19, 2014 at 11:59 pm PDT are eligible for a free code granting access to the Campaign for Halo 3: ODST on Xbox One.
> 2533274803493024;2:
> They are rolling out the codes, yours may just be at the end of the rollout. I got my free month of XBL later than most people did, so this might be a similar thing. Patience, young TERMINATOR333
I received my stuff a little later than most too. Patience goes a long way.
Keep waiting,I got my code this morning but some people ms may just take a bit