I'm sorry, but I don't know what else can be, I tried both DX11 and DX12, no difference, both 2K and 4K, no difference, not a single texture is missing. I can only suspect some kind of antivirus/firewall interference which is messing with the installer. Try this:
- Configure the antivirus to add the whole Addon Manager folder to the antivirus Exclusions.
- Run the FSDT Installer, and Uninstall KIAH, reply YES to both Unlink and Uninstall questions.
- Remove these two folders:
%APPDATA%\Virtuali\UpdateCache
%APPDATA%\Virtuali\PackagesCache
- Reinstall KIAH.