Not much. We suggest a walk around at the start of Spring to check for any loose hardware. You can clean it now and again, but that is up to you. That is about it for maintenance!
For comparison, a wood swing set should be resealed every 1 to 2 years and restrained every 3 to 4 years. Vinyl swing sets are a get-it-and-forget-it. No need to dedicate a few evenings to spending sweating, possibly swearing, and restaining your swing set. Just go inside and watch the game in your favorite chair with a cold drink.