Why do I get this error:
Error getting license
License server communication problem: E_LIC_LICENSE_SIGN_ERROR
I cannot open my .acsm file in ADE
The error says that the back end servers for the place where you purchased the book are not able to talk to the Adobe servers (which are up and available).
You can either complain to the place where you purchased the book, or wait a bit and try again later (assuming that they will notice and fix the problem).
Retrieving data ...