What did I do wrong here for ClickDetector and all?

As pointed out by others, you cannot use elseif with spaces.

You also should not be using deprecated events. Switch from connect() to Connect(). You should also be using local on most of your codes.

A fix to your code.

-- [Declaration Section]
local Up               = script.Parent.Up;
local Down             = script.Parent.Down;
local Left             = script.Parent.Left;
local Right            = script.Parent.Right;

--\\ Variables 
local UpOn             = false;
local DownOn           = false;
local LeftOn           = false;
local RightOn          = false;

-- [Processing Section]
local function On_Clicked ()
	if not UpOn then 
		UpOn = true;
		
		up.CFrame = up.CFrame + Vector3.new(0, -0.09 ,0);
   		wait()
        up.CFrame = up.CFrame + Vector3.new(0, 0.09 ,0);

		UpOn = false;
	elseif not DownOn then
		DownOn = true;
		
		Down.CFrame = Down.CFrame + Vector3.new(0, -0.09 ,0);
   		wait()
        Down.CFrame = Down.CFrame + Vector3.new(0, 0.09 ,0);

		DownOn = false;
	elseif not LeftOn then 
		LeftOn = true;
		
		Left.CFrame = Left.CFrame + Vector3.new(0, -0.09 ,0);
   		wait()
        Left.CFrame = Left.CFrame + Vector3.new(0, 0.09 ,0);

		LeftOn = false;
	elseif not RightOn then 
		RightOn = true;
		
		Right.CFrame = Right.CFrame + Vector3.new(0, -0.09 ,0);
   		wait()
        Right.CFrame = Right.CFrame + Vector3.new(0, 0.09 ,0);

		RightOn = false;
	else 
		return;
	end;
end;

-- [Connecting Section]
script.Parent.ClickDetector.MouseClick:Connect(On_Clicked);