This Achievement unlocks at the end of the game if you get 20 points from free throws as a team.
Set up a game using a good team (like Florida) against a weak team (like Hartford) and crank the shooting sliders up in your favour. Crank up the fouls sliders to increase the likelihood of getting sent to the line, or use a second human player to intentionally foul you.
Increase the length of the halves from the pre-game options if you are having difficulty getting 20 before the end of the game.