1.- Go to https://pi.kwarc.info/historic/systems/texlive/2019/
2.- Download texlive.iso
3.- Mount the iso file into a drive, e.g. E: (Windows 10 can mount an ISO directly without additional software)
4.- Open a cmd window
5.- Go to the mounted drive, e.g. E:
6.- Run install-tl-windows.bat --location "E:/” (repository can be either URL to TexLive directory from 3., or a local directory)
https://medium.com/@ptantiku/texlive-offline-installation-for-windows-38aab4e3500b