Hey buddy,
quick question.
is there a nav mesh in the scene?
you should probably run the animation on begin play inside the spawned actor as it may be an ordering issue, the play animation node may be called before the actor is spawned.
if you want to spawn a predetermined amount of animals you can use a for loop with an int plugged into it, just set the int with the amount of animals you want to spawn (remember that int is 0 indexed)