The Certified Scrum Trainers® (CSTs®) operate as independent businesses, and as such they are responsible for creating and managing all aspects of their courses, including course registrations, payments, and receipts. Since their systems are separate from ours your best option is to contact the trainer or training organization for your receipt.
If you require assistance locating your trainer's contact information, please visit the Course Search page to find your trainer, or you can reach out to us at Scrum Alliance Support.