Centralized procurement and centralized bidding refer to the bidding negotiation in the hospital, and the money is paid by the hospital itself. Hospital staff and product manufacturers sit together for a meeting, and the manufacturers quote and introduce their products. Then the people in the hospital agree to score and finally decide whose products to buy. That's it.
Attention should also be paid to bidding: preliminary work and final quotation. The preliminary work is not done well, and the basic bidding is hopeless.