You have to be enrolled in the Windows Insider Program and be able to get Windows 11 through Windows Update. If you're not in the Windows Insider Program and/or not able to download Windows 11 due to not meeting the requirements for Insider Program then I believe you can't download the latest build via the Microsoft Insiders Program ISO download page. If that is not the problem you're facing then wait a few days to see if it's a generic problem that Microsoft resolves.
I am enrolled in the insider program, installed w11 the second it was available. Hope it's just a generic Microsoft problem they'll fix, will check back on the download in a few days or so.
