Hi hampton123 - Thanks for reaching out.
As you identified in the link you shared, Azure Storage supports custom domain, however it is supported via http.
In order to work with custom domain over https (secure) specifically, you need to with either Azure Frond Door or Azure CDN (explained in the bottom part further). That's where the AFD mainly comes into picture to enhance the security aspect.
The below reference links shall be helpful ahead as well:
https://video2.skills-academy.com/en-us/azure/frontdoor/scenario-storage-blobs#custom-domain-names
Please let us know if you have any further queries. I’m happy to assist you further.
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