Here is sample code to get Co-Author working on author page

<?php get_header(); ?>
<div id="content" class="grid_8 <?php echo of_get_option('blog_sidebar_pos') ?>">
	<?php

	global $coauthors_plus;
	if (isset($coauthors_plus)) {
		$curauth = $coauthors_plus->get_coauthor_by( 'user_nicename', $author_name );
	} else {
    		if(isset($_GET['author_name'])) :
      		$curauth = get_userdatabylogin($author_name);
      		else :
      		$curauth = get_userdata(intval($author));
    		endif;
	}

  ?>
  <div class="author-info">
    <div class="header-title"><h1><?php _e('About:', 'theme1965'); ?> <span><?php echo $curauth->display_name; ?></span></h1></div>
    <p class="avatar">
      <?php if(function_exists('get_avatar')) { echo get_avatar( $curauth->user_email, $size = '120' ); } /* Displays the Gravatar based on the author's email address. Visit Gravatar.com for info on Gravatars */ ?>
    </p>

    <?php if($curauth->description !="") { /* Displays the author's description from their WordPress profile */ ?>
      <p><?php echo $curauth->description; ?></p>
    <?php } ?>
  </div><!--.author-->

You can also add the other co-other fields if the plugin is enabled, just test for it.

$curauth->display_name
$curauth->first_name
$curauth->last_name
$curauth->user_login
$curauth->user_email
$curauth->linked_account
$curauth->website
$curauth->aim
$curauth->yahooim
$curauth->jabber
$curauth->description

https://www.ads-software.com/plugins/co-authors-plus/