Recently, there have been several forum topics around
UNAUTHORIZED_ACCESS. Some examples include:
As this post states:
If you receive a 401
UNAUTHORIZED_ACCESS, the likely cause is that your authentication credentials were missing or incorrect.
We strongly recommend using twurl:
Twurl is like curl, but tailored specifically for the Twitter API. It knows how to grant an access token to a client application for a specified user and then sign all requests with that access token.
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.