Creating an action which interfaces with API authenticated via AWS Signature Version 4

In my GPT, I’m trying to create an action that interfaces with an AWS API that is authenticated with AWS Signature Version 4. Basically, Amazon gives you an “Access Key” and a “Secret Key” to authenticate against the API.

In the Authentication box that pops up when I create an action in my GPT, I see radio buttons that let you choose among “None”, “API Key” and “OAuth” for Authentication Type. I select API Key assuming that this is the authentication type AWS API’s use. Then I’m presented with only one text area to enter an “API Key”, however I have two credentials that Amazon gave me, an Access Key and a Secret Key. Furthermore, there is are radio buttons below for Auth Type that give you the option to select among Basic, Bearer, and Custom. Which options should I select to authenticate against AWS API’s and where should I enter the Access Key and Secret Key AWS gives me?

Thank you,
Mete