The S.GP RD community "about" tab tells this:Really? I mean there are also other Communities holding events other then RD and SGP. I though the idea was to make it public to join after the beta phase. Would be much of a hassle and administrative extra work when you have to first make an account here, pay premium, write an email to the admins to get a "join" link and then connect via steam. But maybe I am missing something once the plattform is launched.
RaceDepartment Club Races and Championships are exclusively arranged for our premium members. To upgrade your RaceDepartment account please visit RaceDepartment.com and learn about the other benefits of going premium.
So yeah, I guess they have a solution for this...
About Discord: iirc you had to link your RD account to Discord. You can see this in "Authorized Apps" in the Discord settings, showing RD forums.
S.GP might do something similar to check if you're premium or not!