It took me a while to find instructions on how to upload my Ren'py game in a web format itch.io recognized, so I thought I would post this for anyone else who might be struggling. It worked for my version, 7.3.5. and was recommended here: https://itch.io/t/1055894/how-to-embed-a-renpy-game-to-my-page.
In the Ren'py launcher, click "Web(beta)," then click "Build Web Application". Under your game folder should be a folder called "[your game]-1.0-dists". Inside is a folder called "[your game]-1.0-web" which contains several files including index.html. Zip "[your game]-1.0-web" and upload it to itch.io as an HTML game.
Hope this helps anyone going through what I did.