I don't want to be very impatient, but does somebody know an solution to my problem??
Hello, it sounds like Digital Editions cannot access the Adobe servers.
There are a couple of things you can try.
First, ensure your firewall if you have one isn't blocking access to the Adobe activation server. Try visiting http://adeactivate.adobe.com. If you can see a 'Welcome to Digital Editions' link, then you should be OK and this is something else that the Adobe technical team may be able to advise on.
You should also check that Adobe Digital Editions is allowed to access the internet on your MAC. Some firewalls block individual programs from accessing the internet, make sure yours does not. Firewalls such as McAfee or Norton usually ask you if you want to allow programs access, there should be some settings in them somewhere to allow Digital Editions access.