Unauthorized Application Api call, but works for Forms and Case

I am using HTTPClient in a C# console app to pull data from the API.

Using basic authentication with a base64 token I can successfully call data from Form and Case using the API. But when I try call data from the Application API using the same credentials it gives me a 401 Unauthorized error.

If I use the same url in the browser and enter the username and password it works fine.

Is there something I am missing?