looks to me as the JVM used to run the ElasticSearch Service is not aware of the root or intermediate CA certificates provided by the GeoIPDownloader Server.
Therefore the validation of the Server certificate fails.
search for the default cacerts file in your configured jvm installation as well as any truststore files in your ElasticSearch installation-
Check how the truststore file are configured in your elasticsearch configuration.
Try to find out which server the GeoIPDownloader tries to connect to and try this invocation from a browser manually to retrieve the certificate presented by this server.
After that try to find out in which truststore (cacerts or elastic search truststores) the ca certificates are stored and if not, add them to the elastic search truststores. Stop and restart the elastic search service after doing so.