The AWS CLI is used to package and deploy your Lambda functions, as well as to set up the infrastructure and security in a repeatable way:

$ sudo pip install awscli --upgrade

You created a user called newuser earlier and have a crednetials.csv file with the AWS keys. Enter them by running aws configure:

$ aws configure
AWS Access Key ID: <the Access key ID from the csv>
AWS Secret Access Key: <the Secret access key from the csv>
Default region name: <your AWS region such as eu-west-1>
Default output format: <optional>

More details on setting up the AWS CLI are available in the AWS docs (https://docs.aws.amazon.com/lambda/latest/dg/welcome.html).

To choose your AWS Region, refer to AWS Regions and Endpoints (https://docs.aws.amazon.com/general/latest/gr/rande.html). Generally, those in the USA use us-east-1 and those in Europe use eu-west-1.