Users get the error: "There was a failure with the mapped account" when attempt to login to StoreFront URL after configuring SAML authentication on the StoreFront server with PingFed IdP

When checked the Citrix Delivery Services event logs from SF, we see below error:

The security token failed validation.
System.IdentityModel.SignatureVerificationFailedException, System.IdentityModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
ID4037: The key needed to verify the signature could not be resolved from the following security key identifier 'SecurityKeyIdentifier
    (
    IsReadOnly = False,
    Count = 1,
    Clause[0] = System.IdentityModel.Tokens.Saml2SecurityKeyIdentifierClause
    )
'. Ensure that the SecurityTokenResolver is populated with the required key.
   at System.IdentityModel.EnvelopedSignatureReader.ResolveSigningCredentials()
   at System.IdentityModel.EnvelopedSignatureReader.OnEndOfRootElement()
   at System.IdentityModel.EnvelopedSignatureReader.Read()
   at System.Xml.XmlReader.ReadEndElement()
   at System.IdentityModel.Tokens.Saml2SecurityTokenHandler.ReadAssertion(XmlReader reader)
   at System.IdentityModel.Tokens.Saml2SecurityTokenHandler.ReadToken(XmlReader reader)
   at System.IdentityModel.Tokens.SecurityTokenHandlerCollection.ReadToken(XmlReader reader)
   at Citrix.DeliveryServices.Authentication.Saml20.SamlExtensions.GetSecurityToken(String assertion, SecurityTokenHandlerCollection securityTokenHandlers)

   at Citrix.DeliveryServices.Authentication.Saml20.SamlManager.ProcessSamlResponse(String base64EncodedResponse, Boolean compressed)
 

1. Request IDP to include the section with the public key into the SAML response after which SAML authentication should succeed.
2. Refer below link to update the assertion and Metadata file as needed - https://docs.citrix.com/en-us/storefront/current-release/sdk-overview.html#example-list-the-metadata-and-acs-endpoints-for-a-specified-store-for-saml-authentication 

Problem Cause