Arcy, yes the screen is put on the inside of the open door so that the door seal will hold it tight when the door is closed. Arcy try this:
Cut out a piece of screen the size of your window except leave 3 extra inches to the outside edge all the way around. Go out to your RV and hold it up to the window (after you open the door! ) and you should be able to visualize from there on how to attach it with the Velcro as I previously described. If this doesn’t help you let me know and I will give it another shot. All that the Velcro is doing is holding it in place until you can close the door to get a seal.