Team Affinity -> Team Standouts: Series 4. Last one on the list.
It doesn't come up in the rewards section, you just need to complete all 32 of the "Team Standouts Series 4" challenges, and you get the free NAT pack, but you dont need to get full stars.
I checked the Team Affinity/Team Builder Challenges but did not see it in the challenge rewards section. Am I loooking in the wrong spot? thank you guys