We have worked as KOA Workampers, but it's been a decade since our last stint with a KOA.
Every job is different in terms of hours and what they consider compensation (site, pay, partial site, etc.) because each KOA is independently owned. Not all offer a free site. Some just offer a discount. Some expect you to work 40 hours/week for only a free site. Others have a lower work requirement. There are other, free, options for finding workamping jobs. Workamper News was one we also followed.