There are three routes to choose from:

20 miles, 972 ft 
37 miles, 1698 ft 
64 miles, 2516 ft

You can find the detailed route information on Ride with GPS:
https://ridewithgps.com/events/205221-spring-rally-2023

The course is open/supported from 10 am - 4 pm,  Sunday March 26th.