There are a couple ways you could make user generated content sections (comments, reviews, and community posts) member only:
Gate pages - If you intend to make pages for user generated only accessible to registered member, we recommend configuring page gating with whichever respective tool you are using: Outseta, Webflow Memberships, and Memberstack.
Gate forms - If you intend to show user generated content to non-members but only want to limit posting content to logged in members, then you can use content gating with whichever respective tool you are using: Outseta, Webflow Memberships, and Memberstack. We also recommend showing an element to logged out visitors, in place of the forms, that says something like 'Join the community to make your voice heard' with a CTA to login. Below is an example of this setup using Webflow Memberships user access settings for elements.