No, that's correct. In order to join the Levels Class you need to be a current member of the Raw Class.
You're right to choose "no".
Then on the next page, you have to choose "Yes, I've taken it in the past, and now I'd like a refresher."
Soft-proofing should be the solution, actually.
But it relies on the labs providing you with a super-accurate soft-proofing profile. Crossing my fingers!