How do I create a photo book from a photo album?

Apple no longer provides printing services for Photo Books, calendars, etc. 

You’ll have to use third-party apps such as Mimeo Photos (who did the actual printing for Apple) or Motif. Both apps are free from the Mac App Store, work with Photos app as an extension, allow you layout and size options, and will guide you thru the submittal process.

https://apps.apple.com/us/app/mimeo-photos/id1282504627?mt=12

https://apps.apple.com/us/app/motif-photobook-album-maker/id1404636482?mt=12

Control (right) - click on t he album and select Create ➙ Book ➙ "your choice of book providers" from the contextual menu:

You may have to go to the App Store to download the apps offered by those providers. I feel the two that are most versatile are Mimeo Photos and PrestoPhoto.