Error receiving PayPal variable

Well, I'm trying to get my php to receive a notification once the payment is made, however I have a problem.

In my paypal notification link I have the following:

link {address_country}

In the paypal api documentation, I see that "{address_country}" is a variable:

link

However, when I insert the variable in the bd, the country does not appear but rather what I wrote "{adress_country}".

Excerpt from my code:

<?php
$country = $_GET["address_country"];

$link = mysqli_connect("localhost", "-", "-", "-");


$sql = mysqli_query($link, "INSERT INTO goncalo (country) VALUES ('$country')");

?>