To enable the SAML (Security Assertion Markup Language) Authentication Handler in Adobe Experience Manager (AEM), certain critical properties need to be configured to establish the necessary trust and communication between the Identity Provider (IdP) and the Service Provider (SP, which in this case is AEM).

A.IDPURL(Identity Provider URL) - This property is essential for configuring the SAML Authentication Handler as it specifies the URL of the Identity Provider. This URL is used by AEM to redirect authentication requests to the IdP. It is crucial for initiating the SAML SSO (Single Sign-On) process.

D.Service Provider Entity ID- This is a unique identifier for the Service Provider (AEM in this context). It is used by the Identity Provider to recognize the Service Provider. The Entity ID is a key component of the SAML assertions and is used to ensure that the SAML responses are directed to the correct entity.

B.Password of Key Storeis important for securing the communication between IdP and SP by encrypting the SAML assertions, but it is not mandatory for the basic enablement of the SAML Authentication Handler.

C.Identity Provider POST URLis used in scenarios where the SAML response from the IdP is sent via HTTP POST. While it's important for the SAML configuration, the initial enablement and basic functionality of the SAML Authentication Handler primarily depend on the IdP URL and the SP Entity ID.