You can use Kentico's baked in user permissions to limit access.
- Create a "limited" role that has basic UI permissions, read / browsetree, but not create/update/delete permissions on pages
- Create your specific role
- Grant access to update/delete/etc on that folder in the content tree through the Properties -> Security
Documentation: Permissions and Page Permissions (specifically Page ACL Permissions should help you out.
If you want to extend permissions to your MVC site, you'll need the XperienceCommunity.Authorization package.