Enable Automatic Login for OS X El Capitan
The Problem
I just did a fresh install of OS X El Capitan. However, I tried enabling automatic login, but it stays locked. It was frustrating.
The Solution
Go to System Preferences, select Security & Privacy to turn off FileVault for the disk.
Go to Users & Groups and click Change Password
Instead of using my iCloud password to log in and unlock this Mac, choose to use a seperate password.
Set my new password
Click Login Options and enable automatic login for my account.
Yay, it worked out!