Local script animation

local script:

local RunAnim = player.Character.Humanoid:LoadAnimation(7171695596)
RunAnim:Play()

why not working?

LoadAnimation expects an Animation instance, not an id, make an Animation instance, put that id as its AnimationId, and reference the Animation instance in the LoadAnimation

local RunAnim = player.Character.Humanoid:LoadAnimation(script.Parent.Handle.Run.AnimationId)
or
local RunAnim = player.Character.Humanoid:LoadAnimation(script.Parent.Handle.Run)
if you mean this not working.

Humanoid:LoadAnimation() is now deprecated. You’d need to use Animator:LoadAnimation() instead, which you’d need to create an Animator with Instance.new(), and parent it to the humanoid.