@wiseupmarketing @granatdesign We are not familiar with this plugin, but I think that we can generalize the solution for you by saying this below:
As long as you are able to add a checkbox field on your checkout page (anywhere), with the name of mailchimp_woocommerce_newsletter
that’s really all you need to do for our plugin to accept the email marketing feature.
Keep in mind that if you’re using the GDPR fields of Mailchimp, you will have to implement them as well manually. We are rendering out the checkbox for you, along with the GDPR fields but if your plugin is preventing this hook from being run, unfortunately our hands are tied, and will be forcing you to implement something manually. If you need any help please feel free to ask, but that’s the solution… a manual edit of sorts.
Hope this helps!