They're on my PC and whenever they type in a name and a password then hit submit, the text on the right just goes red and they can't sign up, even with some random name like gfjdgiosfhg

Their password is probably just too short, as it needs at least six letters.
The red text should say that, even if there's any other delay

Swirlfire a dit :

Their password is probably just too short, as it needs at least six letters.
The red text should say that, even if there's any other delay

And a number. It might also be saying it needs a number.