When you use mac and go to Windows download page then instead of Media Creation Tool you are offered direct link to do download v1909 ISO, but soon it would be v2004.
https://www.microsoft.com/en-us/software-download/windows10
You should also be able to open Boot Camp Assistant and select option 1 to download Win 10 installation files or install from existing Windows 10 x64 USB installer (option 3, selected on my screenshot, example from macOS Catalina).