photos

As you probably know, Apple closed the print product stores more than a year ago. You cannot order books, cards, calendars from Apple at all, even if older versions of Photos or iPhoto are still allowing you to create print products. But you cannot order them from Apple any longer. The message to upgrade to a newer system is misleading. Upgrading will not allow you to order the book from Apple. But you may be able to convert the the book to a version the could be ordered from Mimeo or a similar service. But is is not guaranteed that the book can be converted. See: Post 9/30/2018 Printing Options for Photos

It will be much safer to order the book as described by OT -save the book as a PDF and send it to a different service, Mimeo or Presto Photos.

Which system version do you have installed? The signature is showing OS X 10.10.

To be able to use third-party project extensions to create books for third-party print services you would need to upgrade to macOS 10.13 High Sierra at least.

Are you using iPhoto or Photos? If it's iPhoto are you able to create a PDF file of the book?

If you are able to create a PDF file for that book there's a 3rd party book provider which used to do the printing for Apple as a sub-contractor, Mimeo, that will take PDF files created by iPhoto and Photos and print and bind books and calendars. 

Also you can upload the PDF file to PrestoPhotos which can also print and bind books and calendars from iPhoto or Photos pdf files.  They've been doing it for some time now.  

Use the PrestoPhotos or Mimeo links above for direct access to the PDF file uploading and book/calendar ordering page for each site. 

I've ordered calendars and books from Mimeo and find it's much easier that trying to create the book in Photos with the new extension apps and ordering that way.

Hi Thermort. The steps in this help article may be what you're looking for. There is an imbedded link for the update.

Best of luck.

https://support.apple.com/en-us/HT202358