If you don't have docker installed on your machine or if your docker daemon is not running in the background -> Error: Running AWS SAM projects locally requires Docker. Have you got it installed and running?

STEPS TO RESOLVE THE DOCKER RELATED ERROR

Install docker on your machine
Run sudo service docker start command in the terminal to start docker services on your machine after the installation
Run docker ps to check if the docker services have been started. This command lists all the running docker containers & it works only when docker daemon is running.
Run sudo chmod 666 /var/run/docker.sock on linux if you are not able to start the docker services. More about Unix file permissions
Re-run sh scripts/dev.sh

Provide feedback