How to set animations to npcs?

Hello guys !
So I want to make a horror game , I used Fuse to make like an “alien creature” thing .
I know how to make him follow the player .
But I want the animations that I’ve made for him to be active .
I mean when the player hits the trigger box of the creature and the creature starts chasing the player ,
I want his runing animation to start as soon as the player hit his trigger box , and when the player escapes from the creature or just doesn’t hit his trigger box , I want the creature to be in idle animation .