Cannot download e-book I bought

I bought a book in Grammata (spanish shop). I've asked them, but I've obtained only nonsense anwsers.

I can download the acsm file, but when trying to get the book, it appears an error:

Error on getting the license. Communication problem with license server

E_ADEPT_LIC_TOKEN_NULL_DATA

I don`t know how to debug the error

Thanks