Downloaded Audible books to Apple Books App Using iPad Pro

I’m slowly making the transition from my 2015 MacBook Air to my iPad Pro, but there are still a couple of things that I can’t seem to accomplish on the iPad. I typically download purchased Audible files from my Audible library to my MacBook Air, then associate the files with the Apple Books app. Anyone have a solution for this? I prefer to use the Apple app so all of my books are in the same app, so I don’t want to switch to using Audible.

Any suggestions?