From the Fifa 18 main menu, go to PLAY and choose ULTIMATE TEAM (FUT). In the FUT menu, go to SQUAD BATTLES. This is a new single player offline experience in which you can play against FUT team of other players. You can pick any of the opponents suggested, look for the one with the lowest ranking and chemistry and press
to advance (higher difficulties will gain you higher rewards though). You can pick any difficulty you like, be sure to pick a difficulty that suits you so you can win the game. At the end of the match, the achievement unlocks.