How did the third super quota in AFC Champions League come into being?

China league places 3+ 1, the top two in the league, the FA Cup champion. . If the FA Cup champion is the top two in the league, the runner-up is not the third in the league. . Then the third place in the league will be promoted directly, and the fourth place will participate in the upgrade play-offs. If the top two players in the league are both FA Cup champions and runners-up, then the third player in the league will be promoted directly. . Fourth place in the league participated in the upgrade play-offs