Copying windows installation files

I am using a MacBook Air 2017 macOS Sierra ( version 10.12.6 ) and I am trying to install windows 10 on my Mac, it keeps failing with the error: Boot Camp installation failed An error occurred while copying the Windows installation file, is it possible to fix it without switching to a newer version? ( Mojave or Catalina ) and if not possible I would like to install Catalina and I can not find it in app store, if you can give me a link.