As of the 6.66 patch on 7/20/17, all DLC for the game is free. Along with the patch, multiplayer progression has changed.
The first taunt for this DLC does not unlock until level 38. However, you can unlock other taunts by finishing certain challenges.
Make sure you assign the taunt to the D-pad under Customization -> Taunts. Any time during a match, hit the corresponding direction on the D-pad to unlock this achievement.