Sign in with your work email address, then your password. Nobody gets an account without an invitation from an administrator of their organisation.

After five wrong passwords in fifteen minutes the account is locked for fifteen minutes and you receive an email. The screen gives the same answer for a wrong address, a wrong password and a locked account, so nobody can learn who has an account.

If you forgot your password, use the link under the form. The link it sends works for thirty minutes, and you still enter your authenticator's code afterwards.