simchris
Yes, you can log into the HBO web site if you subscribe via Amazon.
If you subscribe via Amazon, you can download only 1080p via Amazon, but you can also log into HBO and download 4k and 1080p offerings that way.
I find downloading 1080p via Amazon does usually give better video and audio bit rates than downloading 1080p from HBO.
In other words, when I subscribe to HBO via Amazon, I can also log into HBO, but I usually download 1080p via Amazon, and use HBO downloader when I’m trying to get 4k.
My understanding of the HBO subscription via Amazon, it doesn’t include 4k even through the HBO streaming apps and such, but somehow SF has been, and continues to be, able to download 4k from HBO via the HBO downloader.