I'm in the same situation. I'm a registered user with a license for ESXi 6.0, but the buttons
on the download page don't work. (I used two different browsers, cleared all, no cache issues, etc.)
And there's no possible reason to block addresses, from the block of IP addresses
my new ISP uses. 74.123.77.X (There's no hacks out here.)
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I can see some sort of secondary verification, beyond username and password,
but to simply state " it's not possible to download without a VPN ", and even that can be "iffy"....
If I was on your Sales Team, I'd be seriously concerned. Potential customers are not
going to doggedly pursue "why" they can't download. They'll take the path of least resistance
and go to the competition.
(And the competition is probably thanking Akamai for their policy.)