To access invoices/receipts for purchasing credits please navigate to Organization > Billing > Transaction.You should get a list of transactions that you have made as shown:
Image demonstrating how to get invoices/receipts from Pic Siwft CDN dashboard
To download Click on the invoices number highlighted in blue e.g 6271-10034 . Your invoice should download shortly
Incase of any issues on your invoice/receipt please reach out to [email protected]