How to make door stay open if player is within magnitude?

You could make a hinge constraint on the door and set it's Actuator type to Servo. Then when the player comes close enough, you can set the target angle to 90 degrees (or whatever angle you want).

Then when the player leaves, set the target angle to 0 degrees.

The cool thing about this is that also you can change how fast you want the door to open and close by changing the angular speed.

But, that would change alot of stuff

MY REAL SOLUTION

debounce = true
local door = game.Workspace.Door
local sound = game.Workspace.Door.Sound

function onTouched(hit)
    if debounce == true then
        debounce = false
        if (hit.Parent:findFirstChild("Humanoid") ~= nil) then  
            if (hit.Parent.Torso.Position - self.Position).magnitude <=10 then
                if inProgress == false then --if door is closed
                    inProgress = true
                    sound:Play()    
                    door.Transparency = 1
                    -- Here's what i changed
                    repeat
                    wait(1)
                    until (hit.Parent.Torso.Position - self.Position).magnitude >10 

                    sound:Play()
                    door.Transparency = 0   
                    inProgress = false

                end
            end
        end
        wait(1)
        debounce = true
    end
end

script.Parent.Touched:connect(onTouched)