Hi , in this situation you’d probably be better off getting the GitHub version of the engine, downloading all the files and then copying the directory across to the other system. You can download the pre-compiled engine through the launcher and then copy them across, but that’s a long-winded process and you might still be missing a lot of required distributable’s.
In all honesty though, you’ll no doubt regularly want internet access while using the engine (especially as a new user), so I would recommend using an internet connection on the Windows system if you plan to develop on those.
You can find the Pre-compiled engine installs in the same install location as the launcher.