Hi @Hackinet - when a checkout completes, it redirects to your URL and includes a transactionId. You can use this id to call RetrieveTransaction, which would have a customer_id. The address will be a part of the customer, which can be retrieved using RetrieveCustomer.
I hope this helps! If you're still stuck, shoot a message our way so we can connect you with an API team member directly.
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