GA Google Analytics - top-level question for "e-commerce"

A client has the GA JS code inserted for analytics, and it has their UA-123456 acct number.
This HTML/JS snippet is on all their pages, including the one-page creditcard purchase page.
In addition on the creditcard purchase page, there are two additional snippets:
googleadservices.com...conversion.js  and a snippet containing a conversion_id number.
The above three snippets were provided by them for us to insert into the HTML.

they are now asking for e-commerce  tracking.   i'm not familiar with all the aspects of GA, and am wondering what is missing?

Below are the three snippets that exist.

<script>
  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
 
  ga('create', 'UA-nnnnnnn-1', 'theirDomain.com');
  ga('send', 'pageview');
 
</script>
 
 
<!-- Google Code for subscription sale Conversion Page -->
<script type="text/javascript">
/* <![CDATA[ */
var google_conversion_id = nnnnnnnnnn;
var google_conversion_language = "en";
var google_conversion_format = "2";
var google_conversion_color = "ffffff";
var google_conversion_label = "xxnnxxnnxxnn"; var google_conversion_value = 0; var google_remarketing_only = false;
/* ]]> */
</script>
<script type="text/javascript"
src="//www.googleadservices.com/pagead/conversion.js">
</script>
<noscript>
<div style="display:inline;">
<img height="1" width="1" style="border-style:none;" alt=""
src="//www.googleadservices.com/pagead/conversion/nnnnnn/?value=0&label=xxnnxxnnxx&guid=ON&script=0"/>
</div>
</noscript>