r15 animation playing like an r15 rig?

I made an r15 animation on an r15-man rig this gif (I can't get the web links to work) https://drive.google.com/file/d/1FjU9kLGJdp8d5_4tD_l_VU_kj5r6HrZY/view?usp=sharing

where the (looking at the rig) left arm is bending at the elbow, however when I run the animation on a character like here

https://drive.google.com/file/d/1FjU9kLGJdp8d5_4tD_l_VU_kj5r6HrZY/view?usp=sharing)

the same arm doesn't bend.

The game settings are set to only r15 rigs. And I can't find anything online about this.

Here are the important parts of the code that calls the animation

local sawAnim = Instance.new("Animation")
sawAnim.AnimationId = "rbxassetid://3258321733"

local humanoid = character:WaitForChild("Humanoid")

local sawAnimTrack = humanoid:LoadAnimation(sawAnim)

local function playAnimation()-- Play animation track
sawAnimTrack:Play()
end

local function onAnimEnd()
    sawAnimTrack:Stop()
end

local tool = script.Parent
tool.Activated:Connect(playAnimation)
sawAnimTrack:GetMarkerReachedSignal("KeyEnd"):Connect(onAnimEnd)