Granted I’ve only authenticated as a human user via the REST API, but presumably it’s the same across the board: After the Autodesk Identity switch, ShotGrid users need to set up a Personal Access Token before you can authenticate as them.
This is a reasonably complicated topic, but you can read more here: ShotGrid Dev & API consequences and Python API 3.3.1 is out
Once you’ve set up the PAT, everything in your codebase remains the same. However, there’s a fair bit of artist-wrangling involved to get it done, and the users need to be aware that their API credentials are not the same as the Autodesk Id credentials they use to log on to ShotGrid via the website.