Funny level, here's s how i did it:

First i cancel the redirect with pushing esc + cancel, then i read the source code, but i didn’t find nothing, so i use
compare texts web, and i could see that the last js script had different name. Then i compare again the differents js files
and i get the code where redirected me. I change a little bit the code and insert it in the console. Then i could join without the password. My code is this:

a=window.location.host+“”;
b=a.length;
c=4+((510)2);
d=String.fromCharCode(c,-(41-Math.floor(1806/13)),Math.sqrt(b-2)29,(b8)-29);
p=String.fromCharCode(c,-(41-Math.floor(1806/13)),Math.sqrt(b-2)29,(b8)-29);
if(p==d){window.location=“?pass=”+p;
}