unable to open my Ebook

Good morning

I'm trying to open an ebook bought in May. But i can't because appeare a message that m

says my account is not authorized. But this is false. So I tried to download the ebook again from the site where I purchased it and I get this error which I attach as a picture.

How can I do to solve this problem?
I am desperate.It is a book that I need for study.