I feel like I am spinning in circles and can't figure out what I am missing. I have a SharePoint 2016 web application I am attempting to test the REST APIs through Postman with. I follow the guide I found at the following site to authenticate my requests. I get the FormDigestValue, add it to the X-RequestDigest header and make a subsequent request to get the lists on the site. Unfortunately, no matter what requests I make, I get the following response:
"code": "-2147024891, System.UnauthorizedAccessException",
"value": "Access denied. You do not have permission to perform this action or access this resource."
I have gone to the site collection, checked the users permission and the user has Full control permissions. The application is Claims based authentication. Is there anything else that I may be missing to check to get this to work as it does in the guide?