I don’t believe that, definitely the download should contain this “AdvrCntr6.dll”. I doubt with your serial key, can you tell me how exactly you enter your serial key. Do you know that you can even copy past the serial key? Try it entering using the copy paste method.
Few question from my side in order to clear everything and get you a proper solution, did you bought the Nero 11 platinum from Nero online. And also let me know what installer you are executing.