When mapping user attributes, use the providerAttributes prefix rather than samlAssertion as follows:
providerAttributes.<IdP attribute name>	
For example, mapping the email attribute from Facebook to PingOne would look like this:
providerAttributes.email
Note:
For external identity providers that pass attributes in JSON structure (all external providers except SAML), the syntax for mapping attributes that use JSON dot notation, such as name.family, must use square brackets and single quotes around the attribute name as follows:
providerAttributes['name.family']