Third, have an original copy of the doom2.wad file.
Grab both doom2.wad and myhouse.wad files and drop them onto gzdoom.exe. There was also some nice GUI frontends that help you out like ZDL or SSGL, but this is the most direct.
The first I ever saw about MyHouse.wad was when I was sick and having a really bad time and I randomly saw This on my recommend. It made that day a little bit better and threw me down a rabbit hole.
First off, play this MOD!
For French speakers who already played it or for some reason cannot or do not want to play it, this is a great watch: https://youtu.be/FSXI7wctJow
Happiness has to be fought for.
Also for anyone who hasn't played it yet, don't let yourself be spoiled, even by this wiki entry. It's quite the 10 minute map.