When you connect with the natas0 username, you land on a webpage with a box saying "You can find the password for the next level on this page".
There also is a button "We Chall — SUBMIT TOKEN" (that does nothing interesting).
Simply examine the page source code. You will see this line:
<!−−The password for natas1 is gtVrDuiDfck831PqWsLEZy5gyDz1clto −−>