Works well but would like to integrate site user signups

It’s working well for me so far as purely a mailing list signup mechanism. However, I’d like to be able to add new site member signups to the mailing list too (with their permission, of course). (I have Paid Memberships Pro on one site, which I did have working with Mailchimp, and LearnPress with WooCommerce on the other.) Not sure I’m techy enough to get to grips with using Zapier or some other middleman app to do this!