How can I create new listings for set or bundle product via API?

You should first select a category that can be composed of the set product. Please check the attached file and select a set category suitable for the product to be registered. 

 Example) "5 types of skincare for women 1 set". 

• Category ID: 56180 Skin>Basic Set>Set of 4 or more
• Mandatory Options: 수량
• Option value: 1세트