Autodesk Platform Services (APS) Authentication (OAuth) error

I’m trying to implement 3-legged authentication for APS using this source and this source.
I’ve written C# code that generates the authorization URL and opens it in the browser for the user to sign in.
This is the URL I end up with

https://developer.api.autodesk.com/authentication/v2/authorize?response_type=code&client_id=client_id_here&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth%2Fcallback%2F&nonce=1232132&scope=data:read&prompt=login&state=12321321&code_challenge=fePr9SDGJIToHximLHTRokkzkfzZksznrDIx9bexsto&code_challenge_method=S256

However, when I open it, I get the error page at signin.autodesk.com/request-error.

To troubleshoot, I tried sending the same request through Postman, but the response doesn’t include any useful details or error codes.

{
    "developerMessage": "The requested resource does not exist.",
    "moreInfo": "https://aps.autodesk.com/en/docs/oauth/v2/developers_guide/error_handling/",
    "errorCode": ""
}

For some reason errorCode is empty and there is no such error in error handling.

Is this a known issue, or am I doing something wrong?