I just bought the Nikon D750 and cannot open in lightroom. I installed the new update for it, but now it's like lightroom is starting all over again and asking for my serial number (which I can't find). I'm on creative cloud... I shouldn't need to provide a serial number right?
As I don't use the Cloud, one of the few things I know is that no, you don't need a serial number.
Although your'e on CC, you've downloaded the "standalone" rather than the CC version, (which is installed via the CC Desktop app), by the sound of it.