Hi Don,
you should not add any classes in order to make the Ajax Filters to work.
It is hard to identify the problem without checking your site, but I will start with the most common mistakes.
If you have custom category templates please follow this article: https://www.nop-templates.com/ajax-filters-plugin-for-nopcommerce-documentation#addcategorytemplate
About the infinite scrolling, again you should not add anything ( neither classes nor elements ). The only thing that needs to be present in the code is the pager. It should be something like this:
<div class="pager">
<ul>
<li class="current-page"></li>
<li class="individual-page"></li>
<li class="next-page"></li>
</ul>
</div>
<!-- SAL-e, Bottom Banner -->
<div id="google-ads"></div>
<script>// <![CDATA[
(function() {
var script = document.createElement("script");
script.src = "//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js";
script.async = true;
document.body.appendChild(script);
var ins = document.createElement("ins");
ins.class = "adsbygoogle";
ins.style = "display:inline-block;width:728px;height:90px";
ins.setAttribute("data-ad-client", "ca-pub-8453972048291109");
ins.setAttribute("data-ad-slot", "4726471878");
var googleAds = document.getElementById("google-ads")
googleAds.appendChild(ins);
(adsbygoogle = window.adsbygoogle || []).push({});
})();
// ]]></script>