When you made your donation, did you also fill out the form so we can match the donation?
http://www.bierbuden.de/form/de/form.html
If the autoupdater has installed everything, then go to Multiplayer/Internet, then you will probably be asked for your online key, please enter it. Then there should be a button at the bottom right with create, click on it and create a lobby account, you need it independently of the account here on the homepage. Then with driver name and password to login.
The autoupdater has made all the necessary settings and otherwise, as I just explained and as I linked hours ago, you can even see pictures of what to do
Glück auf!