Have you figured this out yet? I found an option that could work for you. Would need to embed some HTML onto your site (Add Elements > Embed & Social > Embed Code). This is for Wix Studio
Then the code I use is this:
<script src="https://apis.google.com/js/platform.js"></script>
<div class="g-ytsubscribe" data-channelid="Channel-ID-Here" data-layout="full" data-count="default"></div>
Just make sure to update the data-channelid to whatever your channel ID is. And if you’re not sure what your channel ID is, just google YouTube channel ID finder and there’s a bunch of tools out there to help you find it.