In step 1 when I click the link, it asks me for an authentication password. What's that?
The links you have clicked are on FTP servers. It's possible that those FTP servers were protected with a username and password. You might need to look somewhere else for drivers. You can download the drivers through the Lenovo website. The driver is compatible with Windows 8.1 on both 32 and 64bit.
Download URL: http://support.lenovo.com/us/en/downloads/ds032125