I can't launch Summer Reborn in Intent launcher, I have the Summer Reborn 3.1

It says that the client needs to be updated, how do I fix?

One delete the client from your intent launcher versions folder and try redownloading it

I did that but it keeps saying the same thing, I heard they stopped working on it or smth, whats that about, and won't I be able to fix this?

One they stopped working on over a month ago. It no longer bypasses on hypixel, and if there’s an issue they won’t fix it. It seems like you’ll have to use a different client.