There is no such thing as a 'free' AWS account. All accounts are full, production accounts. You will always need to provide a credit card to use AWS (or sign-up for invoicing). If you wish to try some AWS service, you can take advantage of the Free Usage Tier.
The AWS Free Usage Tier provides a limited quantity of some AWS services at no charge. When you exceed the quantity of usage (eg hours of an Amazon EC2 t2.micro instance, amount of storage in Amazon S3), then you will be charged normal rates for the service.