Hi SanjayP,
I have an example for an SP, the Adobe Cloud.
It is handled the same way as the Microsoft Auth Page, you need to first specify a NameID (first.last@domain.com) and then the Authenticator recognizes the @domain.com and is redirecting then to the IdP.
Documentation from Adobe: https://helpx.adobe.com/enterprise/using/set-up-identity.html#set-up-directory
So how is it supposed to work when we have a button on this logon page?
So we have for every organization buttons on the logon page then?
I think this will not scale.
Do you understand now what hpr means?
In this example:
Open adobe.com logon page -> Enter first.last@domain.com -> Adobe does the redirect to the IdP for @domain.com.
What you mean is the way it is done with OAuth 2.0/OIDC where the big players like google/github/twitter etc. have bnuttons for login.
In SAML it is different solved, see the manual above from adobe.
I hope this helps to enlighten the question above a little bit.
Thanks,
Peter