UnionPay authentication codes generally need to be applied for and obtained at a UnionPay institution. The specific steps are as follows: 1. Find the UnionPay certification agency. You can find the address and contact information of the certification body on the UnionPay official website. 2. Prepare materials. According to the requirements of the UnionPay certification agency, prepare company registration certificate, tax registration certificate, business license and other materials. 3. Apply. Go to the UnionPay certification agency, apply at the processing window, and submit the prepared documents. 4. Pay the fee. Application for a UnionPay authentication code requires payment of a certain authentication fee. 5. Audit and certification. The UnionPay certification agency will conduct audit and certification and provide the UnionPay certification code to the applicant. It should be noted that different UnionPay certification agencies may have slightly different requirements and procedures. You can consult the staff of the certification agency for details.