🙂 hey there, I read before other people with the same issue. I hope this helps.
After a long chat conversation with some one (I believe were several diferent persons) I got the answer.
You must download the app, then download the e-book and open it using the app.
The books are not automatcly stored in your adobe account. You must go to your suppliers site and donwload each e-book to all your (up to 6) devices.