There is no option for a buyer to say they have received the item.
Usually, if the item is sold as a collection only item, the buyer gets a code to give you.
As you listed with postage, they won't have been given a code so you will have to wait 14 days from the transaction date for payment.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)