Request for a Hidden Page with Automatic Form Submission

I am working with a client who has a specific requirement. They would like me to create a hidden page on their website where only certain individuals can access it through a login. The page would contain a form where users can enter their name, surname, email address, and phone number. However, my client wants these details to be automatically added to a page once users submit their information.

I wanted to ask if this is possible on Squarespace? Is it possible to have a form that automatically populates a page with user data upon submission? If so, could you please guide me on how to do this or suggest any third-party integrations that can help me achieve this?