Downloads don't work / 504 Gateway Time-out errors

I’m trying to download Cubase 12 Pro on a new MacBook Pro, but the links to download don’t work.
The link from the Download Assistant installer page just opens about:blank
The individual software components page also just open about:blank
When I copy the link contents, for example https://www.steinberg.net/sda-mac and try to open it directly from the address bar, I get a 504 Gateway Timeout error page.

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