The correct way to load animations is using the Humanoid animator, so it would be Humanoid.Animator:LoadAnimation(youranimation)

Example:

local UserInputService = game:GetService("UserInputService")

local Player = game.Players.LocalPlayer
local Character = Player.Character or Player.CharacterAdded:Wait()
local Humanoid = Character:WaitForChild("Humanoid")
local Animator = Humanoid.Animator

local Animation = script.Animation
local AnimationTrack = Animator:LoadAnimation(Animation)

UserInputService.InputBegan:Connect(function(input, gameProcessed)
    if gameProcessed then return end -- here we ensure this doesn't trigger if the player is typing in the chat
    if input.KeyCode == Enum.KeyCode.LeftControl then
            AnimationTrack:Play()
    end
end)