No, it is not a must to have a knowledge of Chinese medicine in order to practice PaidaLajin. Anyone can do it. And numerous people across the world who know nothing about Chinese medicine are practicing and benefiting from PaidaLajin.
In Paida, we mainly slap on specific body regions and then the entire body. It stimulates the main meridians and acupoints in the body. In Lajin, almost all tendons and ligaments are stretched in one posture.