Authenticating to download user report JSON

We use integrations with Slack and Trello for User Reporting, but the amount of information posted is a bit lacking, and we'd like to preserve it for longer than the Unity dashboard does. We'd like to be able to download the full JSON via script/command line/etc, and we know the URL we need to use, from the dashboard:

https://dashboard.unity3d.com/app/d...rojects/PROJECT_ID/reports/REPORT_ID/download

The problem is we've been unable to get authentication working in order to do that from script. I tried getting an access token via the method documented here, or directly from my browser session. However the download endpoint does not accept my Authentication: Bearer header with either of those tokens, and only wants to redirect to an auth page.

Can you let me know the header/method I can use to authenticate and reach that endpoint? Thanks!