As the achievement states, you will need to play a game with a duo in MyTEAM. You should have gotten at least 1 half of a duo in your starter cards. Any player that is in a duo will have a symbol with 2 players on the front of their card. If you flip it over and scroll through the attributes, you will see who their partner is. Buy this card from the auction house and start any game mode with both players in the lineup. The achievement unlocked for me on the load screen.
Here is a list of all current duo cards: https://2kmtcentral.com/19/players/duo/1