WooCoommerce Membership: free membership on user registration?

I have to complete my membership site www.yogamiora.com with a feature: user registration must grant access to a free membership plan.
I have tried this plugin on CodeCanyon: https://codecanyon.net/item/woocommerce-membership-free-membership-on-user-registration/13744812, but it is broken and the author is not getting back to me since more than a month.

Any suggestion for other plugins or custom coding?

Thank you very much,