When you download your validated results from Zerobounce you are sent a password in email to access the zip file you downloaded.
The password should arrive in email soon after you download your results. Every Time you download any results, even if its the same results a new password will be sent to you.
We do this for the security of your data, if you left your PC un-attended or if someone got access to your account. They wouldn't be able to get access to your data without the password that's emailed to you.
2-factor authentication is very important.