How do I import photos to the Photos App on iPad Pro?

I am trying to import my Wedding Photos to the Photos app on my new iPad Pro so that I can make a book via the Motif app. My photos currently exist in the following places:

• External Hard Drive
• Amazon Photos (Online)
• Files app

I was able to download the photos from Amazon Photos to a Shared Album in the Photo App, but I cannot access a Shared Album with the Motif app to make the actual book. So I need to some how import my photos from one of these places into an Album in Photos. Is this possible?

I sold my MacBook Pro for this iPadPro and was playing to see if it could replace my laptop. This has been the first big problem I have come across.