Hi @FromZed,
The link from the original announcement is mislinked and its misleading. You must start the Epic Games Launcher. Click Samples from the top bar and then scroll down is City Sample.
Click the “Free” then select the location which should be a hard disk to permanent store at its over 99GB.
I can tell you are using the Epic Games MarketPlace WEBSITE not the app that’s why it says “unavailable” because the EG Launcher is not enabled.
Good luck finding the approx 99GB download space.
I downloaded mine overnight!
on my 2TB drive