Don’t use duct tape, if you rent, the adhesive hardens and will get left behind. Using like packing tape or maybe something professionals use would be better. If the door is metal, they make magnetic curtain rods, we use them on our doors but there will be a limit to the weight of the curtain it can support. Paint on the windows may work, and scraping it off later should work, but is a pain and can scratch the glass.