I dont think you are missing anything, I would try and register for a new linux key.
This is the license key for Linux that is on the RC1 download page
i have the same error on a Windows Vista Ultimate x64 System.
The installation runs well, but the Serial is invalide?
I try the Serial from the Download-Webpage : 98DF1-RDX4K-K5QDH-4RNJT
Please help me.