Visual Studio 2017 download location

Maybe, you can look at the following referrences:

https://docs.microsoft.com/en-us/visualstudio/install/create-an-offline-installation-of-visual-studio

https://www.hanselman.com/blog/HowToMakeAnOfflineInstallerForVS2017.aspx

on my machine, the location is here:

C:\ProgramData\Microsoft\VisualStudio\Packages\