Auto login with FileVault in El Captain
If you want to automatically log in, you need to disable FileVault. A permanent work around would compromise your encryption entirely as described in this Support Article

You can use the fdesetup command to do a one time, immediate reboot and bypass the user log in step. This is designed for unattended reinstallations and works well in my experience if you need to restart and will be attending it physically so as not to lose control of your encrypted system.


https://support.apple.com/en-us/HT202918