change the values on vars.json file with the 4 key names according to your AWS account values: "aws_access_key", "aws_secret_key", "subnet_id"
after cloning the folder to your local folder, run the following command line in your terminal cd packer packer build -var-file vars.json ami.json
Waiting for the processing finnished, the AMI id will appear. Copy the AMI id for the infrastructure project.