To use PDCpay as a vendor you need to enable PDCpay inside your product settings. 

1. When you create a new product at step 4. Checkout & Affiliate or on your existing product, click Edit and go to step 4. Checkout & Affiliate. 

2. Make sure you used PayPal Commerce Platform as Payment method.

3. Under Affiliate Program, you will find a checkbox which says Enable PDCpay. Click the checkbox to enable PDCpay. 

4. Complete the rest of the product creation process or in case of existing product, click Next & Save.