"This option is supported for all authentication methods that receive external user names."
More properly, the authentication methods supported are: ident, peer, gassapi, sspi, and cert.
LDAP is not supported and attempting to use map with LDAP provides the following error: 'authentication option ""map"" is only valid for authentication methods ident, peer, gssapi, sspi, and cert'
This is correct. LDAP authentication does not receive external usernames. It uses an external service to validate the password, but it gets the username from the client.
