Allow users to choose if they are an internal or external user on a login landing page.

We are currently using https://dxc.my.workfront.com/login to bypass SSO for Agencies/External users.

We would like to be able to provide a direct link to forms for those non-SSO users.

The ideal solution would allow users to choose initially if they are internal or external on a landing page so they can be directed to the correct login page when choosing a link to a form from an email.