The buyer would like to put 5 stars to my work but he has already downloaded my recording and the order is completed. Can he do it anyway?
Yes, of course. A buyer can leave a review within 30 days of the delivery.
That´s right, the option is available for 30 days after delivery; ask your buyer to click Buying > Orders in the top menu bar and then click the order you delivered to them and scroll down to the bottom, where they should be able to provide feedback.
You can give them this link too, which describes the process in detail: