Why won't the animation play when the player presses F?

Ok so your formatting is a little confusing but when a rearranged it, it looks like this

game.Players.PlayerAdded:Connect(function(plr)
local UIS = game:GetService("UserInputService")
UIS.InputBegan:Connect(function(key)
    if key.KeyCode == Enum.KeyCode.F then
        local animation = Instance.new("Animation")
        animation.AnimationId = "3560009028"
        local animTrack = nil
        local canPlay = true

        function playShockAnim()
            if canPlay then
                local player = plr
                canPlay = false
                animTrack = player.Humanoid:LoadAnimation(animation)
                canPlay = true
                animTrack:Play()
            end
        end
        playShockAnim(plr)
    end
end)
end) -- extra end)?

I don't understand why you have a function defined when the player presses f instead of just doing what the function does. The real problem is that the animation ID should be "rbxassetid://3560009028" instead of just "3560009028", which is probably why your animation isn't playing, also you should make your animation priority higher so it doesn't get interupted by movement animations.