How to use for loops properly?

SlickPwner is wrong about a numeric for loop only using two numbers. The third, step, is usable, your code is just messed up in other ways.

First of all, your debounce needs to open again after the loop, not inside it.

What it looks like to me is you want to slide the door open, wait three seconds, then slide it shut. This requires two loops, which each need a wait() inside them.

Lastly, you have to add the Door's initial Z-position to the CFrame when moving it, or else it will be set to i, which is why it was teleporting to near the origin.

Door = game.Workspace.Door
Button = game.Workspace.Button

local startZ = Door.Position.Z

local buttonPressed = false

Workspace.Button.Touched:connect(function(hit)
    if not buttonPressed then
        buttonPressed = true
        for i = 5, 0, -.1 do
            Door.CFrame = CFrame.new(86.48, 4.89, startZ + i)
            wait(.1)
        end
        wait(3)
        for i = 0, 5,  .1 do
            Door.CFrame = CFrame.new(86.48, 4.89, startZ + i)
            wait(.1)
        end
        buttonPressed = false --This needs to be outside the loop, or else 
    end
end)

Side note: why does everybody use Spaces instead of Tabs for indentation? It's so annoying!

You have a few problems here. First of all, you have 3 numbers separated by commas in the for line, when you should only have 2.

Secondly, you have messed up the code inside the for loop. I'll rewrite your code, and explain it in comments.

Door = game.Workspace.Door
Button = game.Workspace.Button

local buttonPressed = false

Button.Touched:connect(function(hit) --You don't need Workspace if you already declared the variable.
    if buttonPressed == false then --I prefer "== false" to "not," just personal preference.
        buttonPressed = true
            for i=1,10 do 
            Door.CFrame = CFrame.new(86.48, 4.89, i) 
                wait(.1)
            end
    end
end)

This should work. Hope I helped!