Show put up creator avatar for Final Member

I wish to present avatar from the put up creator. I exploit Final Members and wish to present the avatars which can be outlined by way of UM.

<?php
world $put up;
$url = get_avatar_url( $put up, array( 'dimension' => 48 ));
$img = '<img alt="" src="'. $url .'">';
echo $img;
?>

However this code exhibits the gravatars or default avatar. How can I get the avatars from Final Member?