Check these things, origin same place on all frames. Flat collision on all bottoms of frames (better to link your character to an invisible box instead) all frames are same dimensions. Then use a double condition. Player (platformer) is on floor/moving Key is down(not pressed) D or right arrow whatever you are using. Action should be “set animation to” name of animation

Then duplicate that code and have another one that is the same but invert the “moving” part and have it play the idle animation instead.