Yeah, this part is a bit confusing. I suppose they don't want to deliver the tracks for the remaining location one at a time, which would be too frustrating for the players, and will rather group them in some way.
The tracks are free content, however, and not what's included in the season pass.
Basically, the season pass will bring you a bunch of new cars, liveries and tour events.
I had this issue and fixed it by going to settings -> psn -> restore licenses and then when trying to select the car in driveclub, letting it take me to the store and hitting download again