How can that be?
Before stepping onto the Heavenly Ladder, Yang Chen did not know either.
But when he arrived just now, he had gained some understanding through his analysis. The Ladder contains extremely complex prohibitions, testing the talents and abilities of the geniuses who attempt it. Different trials may be set up for geniuses from different times.
So Yan Haiming is right; it doesn't matter at which stage of cultivation a martial artist is, no one has an advantage or disadvantage over others.
The trials on this ladder test a martial artist's tenacity and strength. It's not enough to just have strong Martial Arts Cultivation; you also need to show sufficient tenacity and strength.