If you would like to restrict access to certain buyers and sellers, you may do that by making your marketplace private. To do so, go to Advanced > Private Setting in your admin dashboard, and toggle the button to “Yes” in the private marketplace settings.
You may choose between “Merchants Only” and “Both Buyers and Merchants” to be registered and verified to access your private marketplace. Following that, you will need to complete the login page template.
After saving your changes, you may then proceed on to manage your buyer and seller lists, sending invitations out to allow private access from your buyer and seller lists.
Here is a video link that will assist you in setting up a private marketplace.