Are you talking about the paper pass ? Sure you can get it delivered anywhere but you need to have it while on the train.

Or about paper seat reservations ? Those are often available online elsewhere. For more precise advice mention route and departure date.

Hola, me refiero al comprar el pase fisico previamente al comienzo del viaje. A través de la página adquiero el pase, y me pide una dirección de envio (mi domicilio). Mi duda es sobre si ese domicilio puede ser el de un familiar(y que esta persona firme la recepción) aunque el pase esté a mi nombre.

You can use any address to have your pass sent to. The delivery address can indeed be different.

But you can also buy the paper pass from a ticket office, also from Renfe as far as I know.