Enabling autologin
Edit the LightDM configuration file and ensure these lines are uncommented and correctly configured:

/etc/lightdm/lightdm.conf
[Seat:*]
autologin-user=username

You must be part of the autologin group to be able to login automatically without entering your password:

# groupadd -r autologin
# gpasswd -a username autologin

LightDM logs in using the session specified in the ~/.dmrc of the user getting logged in automatically. To override this file, specify autologin-session in  lightdm.conf:

/etc/lightdm/lightdm.conf
[Seat:*]
autologin-user=username
autologin-session=session