PMS giving new registrations administrator & customer rights

Hi there, I have the following setup: WP with Beaver Builder, PMS and Woocommerce. I have a registration page which allows one to register for only one type of subscription which is “free”. The subscription is needed before one can access a woocommerce shop (as that is for members only). The role that these registrants are offered as set in the subscription setting page is “customer”. However after registering they are assigned “administrator” rights as well as “customer” rights. This is a significant vulnerability. Please advise, thanks in advance.