Transaction didn’t complete?

Description

I sent a payment to someone . The transaction seems completed from my side, yet that someone claims that he did not receive the money, and in order for him to receive it I need to confirm some kind of receipt…I don’t have this kind of option. And now all of this seems weird. Is there really such a thing that I need to confirm a receipt in order for the other side to receive the money? I have been using PayPal for years, yet this is the first time I encounter with this kind of situation.