How do i make blocks stack on each other?

So my friend gave me this kit he made but he never told me how to make it not snap to grid So i can make a second floor it say's it has a snap to grid setting but it does not work Is there anyway to make it go on top of a placed item if it is hover'd over or if your mouse is in the air it goes off the ground instead of it staying on ground Here is the code LONG CODE

local function enablePlacement(plane, models, prealigned)
    if (plane == currentPlane) then
        return
    elseif (currentPlane) then
        currentPlane:disable()
    end

    if (type(models) ~= "table") then
        models = {models}
    end

    lastRenderCycle = tick()

    currentPlane = plane
    currentBase = plane.base

    local planePosition = currentBase.CFrame * Vector3.new(0, currentBase.Size.Y/2, 0)  

    resting = false
    ox, oy, oz = planePosition.X, planePosition.Y, planePosition.Z
    currentXAxis = currentBase.CFrame.rightVector
    currentYAxis = currentBase.CFrame.upVector
    currentZAxis = currentBase.CFrame.lookVector
    currentAxis = CFrame.new(0, 0, 0, currentXAxis.X, currentYAxis.X, -currentZAxis.X, currentXAxis.Y, currentYAxis.Y, -currentZAxis.Y, currentXAxis.Z, currentYAxis.Z, -currentZAxis.Z)
    currentObjects = {}
    dxx, dxy, dxz = currentXAxis.X, currentXAxis.Y, currentXAxis.Z
    dzx, dzy, dzz = currentZAxis.X, currentZAxis.Y, currentZAxis.Z
    cx, cy, cz, cr = 0, 0, 0, 0

    springVelocity = Vector3.new(0, 0, 0)
    springPosition = Vector3.new(0, 0, 0)

    tweenAlpha = 0
    tweenCurrentRotation = 0
    tweenGoalRotation = 0
    tweenStartRotation = 0

    local position, _ = inputCapture()

    if (not position) then
        position = planePosition
    end

    springPosition = position

    do
        local extentsXMin, extentsXMax = 10e10, -10e10
        local extentsZMin, extentsZMax = 10e10, -10e10

        for i = 1, #models do
            local model = models[i]
            local object = {}
            object.model = model

            local lookVector = object.model.PrimaryPart.CFrame.lookVector   
            local theta
            local px, pz

            if (prealigned) then
                local position = object.model.PrimaryPart.CFrame * Vector3.new(0, -object.model.PrimaryPart.Size.Y/2 , 0)       
                px, pz = project(position.X, position.Y, position.Z)

                theta = math.acos(math.clamp(lookVector:Dot(currentZAxis), -1, 1))
                local cross = lookVector:Cross(currentZAxis)

                if (cross:Dot(currentYAxis) > 0) then
                    theta = -theta
                end

            else
                px, pz = object.model.PrimaryPart.Position.X, object.model.PrimaryPart.Position.Z
                theta = math.atan2(lookVector.X, lookVector.Z)      
            end

            local x, z = model.PrimaryPart.Size.X, model.PrimaryPart.Size.Z

            object.r = round((theta % (2 * math.pi))/(math.pi/2), 1)

            if (object.r == 1 or object.r == 3) then
                x, z = z, x
            end

            local x1, x2 = px + x/2, px - x/2
            local z1, z2 = pz + z/2, pz - z/2   

            if (x2 < extentsXMin) then
                extentsXMin = x2
            end
            if (x1 > extentsXMax) then
                extentsXMax = x1
            end

            if (z2 < extentsZMin) then
                extentsZMin = z2
            end
            if (z1 > extentsZMax) then
                extentsZMax = z1
            end


            model.PrimaryPart.Transparency = .5
            model.PrimaryPart.Anchored = true
            model.PrimaryPart.CanCollide = false

            setState(object, plane.loading and states.loading or states.neutral)

            currentObjects[i] = object
        end

        currentExtentsX, currentExtentsZ = round(extentsXMax - extentsXMin, currentPlane.grid), round(extentsZMax - extentsZMin, currentPlane.grid)

        for i = 1, #currentObjects do
            local object = currentObjects[i]
            local px, pz

            if (prealigned) then
                local position = object.model.PrimaryPart.CFrame * Vector3.new(0, -object.model.PrimaryPart.Size.Y/2, 0)        
                px, pz = project(position.X, position.Y, position.Z)
            else
                px, pz = object.model.PrimaryPart.Position.X, object.model.PrimaryPart.Position.Z
            end

            object.px = px - (extentsXMin + extentsXMax)/2
            object.pz = (pz - (extentsZMin + extentsZMax)/2) * (prealigned and -1 or 1)

            object.sx, object.sy, object.sz = object.model.PrimaryPart.Size.X, object.model.PrimaryPart.Size.Y, object.model.PrimaryPart.Size.Z
        end
    end

    renderConnection = runService.RenderStepped:connect(run)
    module.currentPlane = currentPlane
    currentEvent = Instance.new("BindableEvent")

    if (GRID_TEXTURE) then
        currentTexture = Instance.new("Texture", currentPlane.base)
        currentTexture.Texture = GRID_TEXTURE
        currentTexture.Face = Enum.NormalId.Top
        currentTexture.StudsPerTileU = currentPlane.grid
        currentTexture.StudsPerTileV = currentPlane.grid
    end

    bindInputs()

    run(true)

    return currentEvent.Event
end