How do I restore my files?

There is no restore button in the app. Your copy is made of regular files and folders, with no special format, so you can copy anything back yourself at any time. For a Live Photo, take the image and the movie file together, because they belong to one item.

On Mac

In Finder, drag files back where you want them. To put photos back into Apple Photos, drag the folders into Photos, ideally into a new Photos library.

On iPhone and iPad

Open your backup in the Files app, start dragging the items, switch to the Photos app while you keep dragging, and drop them onto the Library. This is much easier on iPad than on iPhone.