Everyone who gets in game needs a game key to do so. You should have received one when they let people in a while back. Check your email, spam folder, and any other folders that mail might get diverted to.
If you don't find it, check and make sure your email address connected to this account is still current. If you have been receiving the monthly newsletter as of Feb, then it is.
The Knight's pledge has Champion testing access, but it's an odd pledge so you need to submit a ticket to Support to get them to change your status from Supporter. If you don't find the email, they'll be able to help with that too.