https://community.arubanetworks.com/t5/Learning/Clearpass-Guest-log-in-automatically-without-clicking-the-log-in/td-p/296995
On Receipt Page UI
Footer HTML:
{if $user.enabled}
<script type="text/javascript"><!--{literal}
addLoadEvent(function() {
Nwa_SubmitForm(_form_name,"ID_"+_form_name+"_submit");
});
//-->
{/literal}</script>
{/if}