@BenjaminNamika1 You're welcome :)
@BenjaminNamika1 .env's should work for other people, they will not just be visible publicly. Though I'm not sure, I'm not a "real" repl user. You should ask someone that knows better or look at the docs of repl.it.
Be careful not to put publicly your jsonstroe token.
I entered a taken username in register, it says to take another one, and then it immediately says to choose a password
Also, I started the thing, said register, and while it was saying the instructions I pressed enter, so at the registration step it said "This username has been taken, please enter another username" and it didn't let me enter one.
After registering, I typed "loby" instead of "lobby", and so the program crashed and I need to run it again. Otherwise that looks cool! Though it may need some English improvements.
Well, as others said, it's an embed of classic.minecraft.net. You haven't really made it. You should credit the original site.