I just made a transaction, I am quite satisfied with the whole process. Maybe I'll write a complete review somewhere.
What confuses me is entering the Refund address, which is not mandatory, but can be added later. However, during the process, I did not have the opportunity to enter it afterwards. Did I overlook it and why is it not mandatory? If a refund of the address was required, would I have to request a refund from support and what does that process look like?

I admit that the explanation on the website is not the most specific.