How to get Lightroom 6 serial of purchased DVD-version?

Hello, I just purchased the box version of Lightroom 6 including DVD. Within this box there is a Code with which I should be able to get the serial number to finish my installation. So I used my Adobe ID, which I have created to use the 30 days trial version before. But at the end I don´t get any serial number, with the information I don´t need the serial number but should download the Creative Cloud. What am I doing wrong? How can I get the serial number? Help would be much appreciated.