During a direct user authentication, this is the URL to Authenticate a user with (provided by your SAML 2.0 provider).
SalesForce Connected App Example
If your SAML 2.0 connection is to a SalesForce connected App, in the SAML Login Information you would copy the SP-Initiated Redirect Endpoint to this property.
OKTA SAML Integration
For an OKTA SAML 2.0 application, this URL is found from either the initial definition or editing and is accessed from the Sign-On Tab:
The value is 1, Identity Provider Single Sign-On URL:
Active Directory Federation Services
This is the value that is entered in the Relying party WS-Federation Passive protocol URL property
