I'm assuming you're trying to boot the machine. Barnfather is saying that you'll need to enter your password for the first boot (similar to iOS where your passcode is required to activate Touch ID). This is probably because of FileVault encryption. Your password will be required on first boot, but then you can authenticate with Touch ID once access has been granted.
It works the same way as the iPhone or iPad. When you restart your phone, you have to enter your password so that the phone recognizes you from that point forward. The new Mac is no different.