How would I be able to track player speed?

I made this hoping I will be able to track the speed of players but it always shows 0m/s

-- Create a new screen GUI
local screenGui = Instance.new("ScreenGui")
screenGui.Name = "SpeedTracker"
screenGui.Parent = game.Players.LocalPlayer.PlayerGui

-- Create a frame to hold the player speed labels
local frame = Instance.new("Frame")
frame.Size = UDim2.new(1, 0, 1, 0)
frame.BackgroundTransparency = 1
frame.Parent = screenGui

-- Create a label for each player
for _, player in pairs(game.Players:GetPlayers()) do
  local label = Instance.new("TextLabel")
  label.Size = UDim2.new(0, 100, 0, 20)
  label.BackgroundTransparency = 1
  label.Text = player.Name .. ": 0 m/s"
  label.Parent = frame
end

-- Update the player speed labels every frame
game:GetService("RunService").RenderStepped:Connect(function()
  for _, player in pairs(game.Players:GetPlayers()) do
    local label = frame:FindFirstChild(player.Name)
    if label then
      label.Text = player.Name .. ": " .. player.Character.Humanoid.WalkSpeed .. " m/s"
    end
  end
end)

not sure if this will work, but try doing this. add a Server Script and add a ScreenGui to starter Gui

 game.Players.PlayerAdded:Connect(function(plr)
	plr.CharacterAdded:Connect(function(character)
		local frame = Instance.new("Frame")
		frame.Size = UDim2.new(1, 0, 1, 0)
		frame.BackgroundTransparency = 1
		frame.Parent = plr.PlayerGui:WaitForChild("ScreenGui")

		local label = Instance.new("TextLabel")
		label.Size = UDim2.new(0, 100, 0, 20)
		label.BackgroundTransparency = 1
		label.Text = plr.Name .. ": 0 m/s"
		label.Parent = frame
		while wait() do
			label.Text = math.ceil(math.abs(character.HumanoidRootPart.AssemblyLinearVelocity.X + character.HumanoidRootPart.AssemblyLinearVelocity.Z)).."m/s"
		end
	end)
end)