An IAM user was given an access key rather than a password. What is that access key intended to be used for?

An access key, consisting of an access key ID and a secret access key, is a programmatic credential. It is designed for making authenticated requests to AWS services directly from applications, the AWS Command Line Interface (CLI), or the AWS SDKs. Therefore, using it to access the AWS account through a CLI is the correct use case. Accessing the AWS account as the AWS account root user is incorrect because the root user has its own credentials (email and password) and should only be used for a few specific tasks. Accessing the AWS Management Console requires a password, not an access key. Accessing all of a company’s AWS accounts is incorrect because an IAM user's access key is tied to a specific IAM user within a specific AWS account and its permissions.