Enable Automatic Login for OS X El Capitan

The Problem

I just performed a fresh install of OS X El Capitan. I attempted to enable automatic login, but it remained locked. This was frustrating.

The Solution

1. Go to System Preferences and select Security & Privacy. Turn off FileVault for the disk.
2. Navigate to Users & Groups and click Change Password.
3. Rather than using my iCloud password to log in and unlock this Mac, I opted to use a separate password.
4. I set my new password.
5. I clicked on Login Options and enabled automatic login for my account.

Yay, it worked!