How to expose an Azure Power BI Report Server url to external clients

I have installed the Power BI Report Server that I found on Azure Marketplace, https://azuremarketplace.microsoft.com/en-in/marketplace/apps/reportingservices.technical-preview?tab=Overview. I can load the web portal from within the vm that this deployment created. How do I now expose the web portal url and the rest api to external clients?

I have the Power BI Desktop app and when I try and connect to this report server by saving a report to it, it fails with error "unexpected error encountered"

Note I can rdp from my network into this vm without any additional configuration, so it is exposed at some level to the internet.