If the automated email hasn't been sent in time or you entered a wrong delivery email, then there is another option to get the code, provided that your payment was successful.
For searching for one of your codes, you have to visit https://dokkansearch.com/findorder and input your Invoice ID (example:b7945ddf-e27f-4c46-731c-f4cd7d21429c) into the field and press "Find my order." 
Afterward, you will get a result. If the status is "The payment was verified" then a Transfer Code is displayed, otherwise not. 
If your status is different from the status "The payment was verified", then please wait for at least 30 minutes and retry entering the Invoice ID. If the status still hasn't changed after half an hour, then please contact us.
Check out the service here: https://dokkansearch.com/findorder