Season pass codes in the ultimate edition

So, I got the ultimate edition of HW2 and got a code in the case saying it was for HWDE and the season pass, although the code only installed HWDE. Can anyone explain if I have to but the season pass or if it is included?

The season pass is included with the purchase of Halo Wars 2 Ultimate Edition. There is no separate season pass code which Halo Wars 2 Ultimate Edition owners need to redeem.

The season pass is included. Go to the game store on the dashboard and look for HW2 season pass it should be installed if not install it.