One of the benefits of purchasing a pre-hung door is that it already comes with a frame, hardware, and hinges. It’s a lot easier and faster to install a pre-hung door compared to a slab door, which is simply, well, a door. If you are replacing your patio door and your frame needs to be replaced too, then pre-hung French doors are a good option.
When you install pre-hung French doors, you need to remember that they are very heavy since the frame comes with them, so make sure to have an assistant ready to help. You also need to finish any electrical work around the area before installing the doors. Once you are ready, you can follow the instructions here on how to hang and finish French doors.