I found this on the error in question.
E_LIC_LICENSE_SIGN_ERROR - This means that our server is unavailable to speak to the Adobe server to validate the Adobe ID. This should be a temporary issue so please leave it a few minutes & try again BUT if you continue to see this error please contact us at
orders@foyles.co.uk and we will investigate further.
http://www.foyles.co.uk/help-ebooks