Trying to save placement of furniture over DataStore and I am getting Error 104; what is the issue?

game.Close:Connect(function()
	local saveFolder = workspace.placedFurniture
	local saves = saveFolder:GetChildren()
	local saveFurnitureTable = {}
	for i = 1, #saves do
		local save = {}
		save["folderName"] = saves[i].Name
		local furniture = saves[i]:GetChildren()
		for i = 1, #furniture do
			save[furniture[i].Name] = furniture[i].PrimaryPart.CFrame
		end
		saveFurnitureTable[i] = save
	end
	local Success, Error = pcall(function()
      return game:GetService("DataStoreService"):GetDataStore("SAVE"):SetAsync("Furniture", saveFurnitureTable)
	end)
	if Error then
		warn(Error)
	end
end)

Output as requested. 104: Cannot store Array in data store. Data stores can only accept valid UTF-8 characters.

I think the problem is that you cannot save instances in DataStore. (Parts, Models, Tools, etc.) Instead, you have to save all the info of the model. (CFrame, Size, etc.)