Thanks for including your app ID. I’ve confirmed that your app ID has been granted access to the Ads API.
UNAUTHORIZED_ACCESS response points to missing or incorrect authentication credentials. We strongly recommend reading the Guidance for UNAUTHORIZED_ACCESS issues page as well as using twurl to help debug authentication issues.
Once you are able to successfully make the request using twurl, you can be fairly certain that there was an issue with your authentication credentials and not with access to the Ads API. If you need further assistance, please visit the OAuth category.