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