That's me - I have downloaded the Schleife before I even have started to download the main program.
Use the link for the Schleife v 2.0 in the youtube explanations. Googling for "GSC Nordschleife" only leads you to two or three resources that offer the file version 1.0.
By chance I found that there is a gravel-track Nordschleife for Richard Burns Rally.