iPhoto - Book Project - Store Update

I am looking to order a book project, but every time i have tried to purchase over the past few weeks I am prompted with "The Store is down for updates. We'll be back shortly." My computer is running on OS X El Capitan v. 10.11.6. I have tried updating all software to no avail.

Any suggestion or help? I am trying to avoid remaking this 100 page book.

Thanks!