Unable to connect to Amazon with AWS Key Pair

I import Amazon items using the WordPress plugin WZone. The Amazon associate page, affiliate-program.amazon.com/assoc_credentials/home, is where I generated my Amazon AWS key pair. The AWS key pair isn't working to get me into Amazon, as it displays the following error:

** Country: United States Amazon Error: ErrCode = 1 | ErrMsg = [[ Amazon API v5: http status code = 429 http msg = [429] Client error: POST https://webservices.amazon.com/paapi5/searchitems resulted in a 429 Too Many Requests response: {"__type":"com.amazon.paapi5#TooManyRequestsException","Errors":[{"Code":"TooManyRequests","Message":"The request was de (truncated...) http x-amzn-RequestId = ccf195b3-f54a-4e00-9bf2-9ab9b4a271f8 errcode = TooManyRequests errmsg = The request was denied due to request throttling. Please verify the number of requests made per second to the Amazon Product Advertising API. ]] WooCommerce Amazon Affiliates was not able to connect to Amazon with the specified AWS Key Pair and Associate ID. Please triple-check your AWS Keys and Associate ID.

Note: AWS website at https://us-east-1.console.aws.amazon.com/iam/home#/security_credentials also shows: Access keys (1) Use access keys to send programmatic calls to AWS from the AWS CLI, AWS Tools for PowerShell, AWS SDKs, or direct AWS API calls. In other words, Amazon has two different websites to create an AWS key pair.

What is the difference between Amazon Associates and AWS? Why do they both create Amazon keys, confusing many?