This is my first game jam and i saw a post saying to make it so it works in the browser, I've only ever used UE5 and apparently you cant do it with that? Do i need to make it work in the browser and will people play it if i don't?
You don't have to make it work in the browser, but generally people prefer to play the games through their browser rather than download an exe file, so you risk having less people play it than if it was a browser build.
Last year plenty of people had download only games though and they still got people playing them so I wouldn't worry about it too much.
Yeah, more people might play it if it's a WebGL build simply because it's less work for the player. As LazarusCraven said, people will still play downloadable-only games. If you only have a downloadable version, consider the following to get as many people playing as possible:
All of these things apply to WebGL as well, to maximize players. It's a game jam, so people are forgiving of poor-ish optimization as long as the game is playable, and no one really expects professional copywriting. But putting in an effort will generally get rewarded with people giving your game a chance since that is usually visible from the person's page. Having a fun (and fun-looking) game helps, too. Good luck!
Additional Note:
WebGL has limitations. If you're not sure what those limitations are, especially for an unofficial solution to creating a WebGL build for Unreal, then it may be better to not even worry about it and just focus on a good downloadable build - otherwise, you might end up spending time on visuals or other gameplay elements that aren't supported in WebGL and will be disappointed.