Those credentials applied to the flatcar OS. For Ignition Cloud to reach the HiveMQ CE Broker in UMH, you'll need to have port 1883 open on your internet firewall, port forwarding applied to your flactar VM's IP, and the Service united-manufacturing-hub-mqtt-external must be exposed externally on the Kafka cluster (I believe this is true by default). The net result of this is a publicly exposed MQTT broker, so I'd also recommend applying whatever security is appropriate for your use case/risk tolerance.