MX Simulator

So, I’m trying to get back into Mx sim racing. I was going to try the latter part of the MX series, so I purchased so points and bought a single event race pass. But when I go to sign up, it says I need to select a series number to race…but there isn’t anywhere on the website I can go to select a series number? My number is set to 616 on my profile. I’ve looked everywhere on the events page, and other pages, to see if I can find somewhere to select a series number and can’t find anything.

Anyone help me out? Thanks!