2D Sprite Animation on a 3D game

Hello, ex-GameMaker user here... There's something that is quite bugging me in Unity. I am making a 2.5D game (3D Map, 2D sprites) just like Paper Mario sort of. I wanna make 2D animations play when I press a key. For example, by pressing S, MoveDown plays. By pressing W, MoveUp plays, and so on. I want to keep it simple, 4 directions only for now.

Forgot something, I want to make the same happen for other characters and not only the player.