I use this code Did not edit anything, because the field uses the same name.
<?php
$users = get_field("volunteers");
if( $users ): ?>
<ul class="volunteers-list">
<?php foreach( $users as $user ): ?>
<li>
<img src="<?php echo esc_attr( get_avatar($user->ID) ); ?>" alt="author-avatar" />
<a href="<?php echo esc_attr($user->user_url); ?>"><?php echo $user->display_name; ?></a>
</li>
<?php endforeach; ?>
</ul>
<?php endif; ?>
