Enable password authentication for the Ubuntu Server in AWS

I created a Ubuntu 18.04 Instance in AWS, then I connected to the instance using the pem file using ssh -i pemfile ubuntu@public-IP

sudo passwd ubuntu
Changing password for user ubuntu.
New password:
Retype new password:

I set the password for the account, then enable the password authentication in the SSH config file

sudo nano /etc/ssh/sshd_config

Find the PasswordAuthentication no 
and set it to yes

PasswordAuthentication yes

sudo service ssh restart

Reference: https://aws.amazon.com/premiumsupport/knowledge-center/ec2-password-login/

Also published on Medium.