Don't think you can use your files from your computer to upload easily. You should click on "upload and share replay" instead of "download replay" for a probably less convoluted method of doing so.I saved a replay, how to I make it find able to others? I'd like to share it with my discord friends, but I don't really know what I'm doing.
The file I saved is as such: file:///C:/Users/Arufa%20Orime/Downloads/Gen7DoublesOU-2019-09-02-nelvini-arufaorime.html
From there, you look for your replay in replay.pokemonshowdown.com .