In Photos 4.0 all tools to create Apple Print projects have been removed. For print projects you have to use third party extensions, because Apple does no longer offer print services at all.
If you are still using Photos 3.0 or an alder version, you can still create Apple books and calendars with the old tools, but you can no longer order them.
Newer versions of Photos (since Photos 3.0) come with the ability to call third-party project extensions from Photos to let us create books or other print projects.
See Apple's announcement: Use Project Extensions to order print products in Photos after September 30, 2018 - Apple Support
"To give users access to a broader variety of print services, macOS High Sierra introduced Photos Project Extensions which integrate directly with the Photos app. In macOS Mojave, Photos will transition entirely to Photos Project Extensions. Users will be able to print and update their existing projects using these new services, and will gain access to a broader variety of options. For final purchases using the existing built-in service, place your orders by September 30, 2018. "
If you are still running an older version of Photos, you can save the book or calendar you craete in Photos as a PDF file and have it printed by a different service: Ordering Books and Calendars on a Mac tha… - Apple Community
For Photos 4.0 see: Post 9/30/2018 Printing Options for Photos - Apple Community