Hello @lonejack
Welcome to the HiveMQ Community! The article provided is focused on the on-premises installation of HiveMQ Broker, like scenarios where HiveMQ is deployed locally.
To connect to HiveMQ Cloud Serverless instance you must upload Let’s Encrypt CA to your device and make sure it supports SNI (Server Name Indication).
You can find more information in our FAQ section at Frequently Asked Questions
Kind regards,
Diego from HiveMQ Team