Sync Content Across Devices?

I'm trying to use DE on my Windows laptop, Android phone and Android Tablet to read borrowed library books, as Adobe software is all it will allow me to use. I can load my books to my computer fine enough, but despite all devices being authorised under my account...the contents of my library isn't shared across them. The books on my laptop aren't available on my phone or tablet. No matter what I do.

To make matters worse, when I try re-download the book onto my phone or tablet from the library's website, clicking on the ACSM file will automatically boot into the app...but then refuse to actually show or load the book. So I'm at a loss. I just want to be able to resume my reading regardless of which of my devices I have nearest me.