Hi again,
Thanks for your help again.
I am afraid it is a network/firewalling related issue. I tried to connect on my machine with hotspot connection and I am able to download the Office locally using command setup.exe /download configuration.xml.
Have you got any information on what kind of prechecks does the setup.exe ODT installer perform?
I reckon I should check that appropriate addresses are accessible on the proxy/FW (see https://learn.microsoft.com/en-us/microsoft-365/enterprise/urls-and-ip-address-ranges?view=o365-worldwide#microsoft-365-common-and-office-online)
Maybe there is also network bandwidth minimum requirements. Anyone have information about it?