How do 30 basketball teams decide the top 16 and then play the knockout round? Specific point

No team played 70 games as assigned. East and west are at war. Finally, the six winners in the East and the six winners in the West add up to promotion. Then two teams in the West will play a series at random, and whoever wins four games first will be promoted. Finally, the western champion was decided. The same is true in the East. East-west championship final