How do I upload both htmlt5 & downloadable files in a single game page? Game like Friday Night Funkin'? I tried finding tutorials about it, But I can't find any. Help?

When uploading files on a game page, you can mark an option as being an HTML playable game. If you have multiple files, and one of them is marked as such, the rest will be marked as downloadable files. You can mark those as being for windows, linux or any other platform.

Hope that makes sense :)

1. Select HTML/browser a your game type
2. Upload the browser version of your game (see https://itch.io/docs/creators/html5) and mark it as the one to be played in the browser
3. Upload the builds for other platforms separately and select the platform for each