How to access ADO work-items from FME ? I explored different ways like providing personal Access Token, Username password but it is giving Status code 203 Non-Authoritative Information

looking at the error message (https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/203)

It suggests that you have a reverse proxy (or something similar) between the ADO server and your FME Server that is altering the payload.

I'd suggest you reach out to you infrastructure team to work through what that might be