Public access to a fusion extended page

Summary:

We have a requirement to build a visual builder page to create leads for external access.

The page should be a public page for external users and their input should create leads in Fusion.
External users should only see this page and won't be able to navigate to any other fusion page (we will share the url of this specific page only to external users)

As per the screenshot above, We have built the page and unchecked the option to require authentication in order to be accessed publicly. Yet it still asks for login credentials when opening the page from an external link.