Visitors being directed to the wrong login page.

I have the “Membership Pro 2” and the “Support System” plugins. I have it set to where only our clients and customers can submit new tickets. When I go in as a non-user, it says “You must log in to submit a new ticket”, which is good. However, it takes them to the wrong login form. I have two different login forms with different URLs. One is a customized login form for the frontend for clients and customers (made with Membership Pro 2) and the other one is the default WordPress login for the backend for site admins and team members. When someone goes to create a new support ticket if they are not logged in, they get taken to the default WordPress login instead of the frontend login like how I want.