This has been happening since at least Saturday, and others have reported this as well (in the regular Hypervisor forums).
https://my.vmware.com/group/vmware/evalcenter?p=free-esxi6
Neither the "manually download" nor the "Download Manager" links do anything.
I've tried 6 different computers (Windows XP and Windows 7 Home and Windows 7 Enterprise), 4 different web browsers (IE10, IE11, Firefox, chrome), and 3 different ISP (Verizon FIOS, Road Runner, and whoever supplies our Corporate LAN--AT&T or something).
I'm not sure VMware is even aware that there's an issue.