Lightroom to the Photos App.

There are NO Folders or Images INSIDE LR.

LR is a Database program that references your images from the folder they are in on your hard drives.

To get LR EDITED images into the Apple Photos app you first need to Export those edited images to a separate folder on your drive.

All Edits done in LR are store in the catalog file and NOT in or with the original image file. LR Never changes the original file. It just overlays the edits you have done and displays them On Screen.

To get those edits in an actual image, to Burn, Include, the edits into the file, for other programs to see them you need to Export the original to a New file.

Once you do that and place those edited, Exported, images in a separate folder then in the Apple Photos app you can import them, make your book and send it to the publisher for printing.

Apple Photos CAN NOT READ the edits done in LR. So the only way to get edited images into Photos is to first Export them and then load those exported, edited, images into Photos.