cannot read e-book on e-reader

A few days ago I bought an e-book.
Unfortunately at that time I forgot all about my adobe account and downloaded it anyway.
Now I cannot read it on my e-reader.
I contacted the store and they mailed me all the steps I had to take, but I still cannot open it.
The file is in my account but when I try downloading it again, the adobe log in does not appear and so the problem stays.