The first packer build command includes passing AWS access key and secret key as variables. On Windows, the single quotes must be replaced with double quotes or an AWS error occurs. This may not be obvious to everyone, hence a note. The AWS error (as below) is not adequately self-explanatory.
Build 'amazon-ebs' errored: Error querying AMI: NoCredentialProviders: no valid providers in chain. Deprecated.
For verbose messaging see aws.Config.CredentialsChainVerboseErrors