you don't configure AWS account in splunk but you can install SPLUNK into amazone EC2(elastic compute cloud) in your AWS account . Sign Up for A WS
When you sign up for Amazon Web Services (AWS), your AWS account is automatically signed up for all services in AWS, including Amazon EC2. Y ou are charged only for the services that you use. With Amazon EC2, you pay only for what you use. If you are a new AWS customer, you can get started with Amazon EC2 for free. For more information, see AWS Free Tier.
If you have an AWS account already, skip to the next task. If you don't have an AWS account, use the following procedure to create one.
T o create an AWS account
1. Open http://aws.amazon.com/, and then click Sign Up.
2. Follow the on-screen instructions.
Part of the sign-up procedure involves receiving a phone call and entering a PIN using the phone keypad.
Note your AWS account number, because you'll need it for the next task.
-to see documentation about all information of AWS account:see http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts.html