How to Enable Authenticated Proxy with the Logged in User in UiPath.
To Redirect the Robots using the Proxy below configuration needs to be configured.
Redirecting Robots through a Proxy Server
However in case the Proxy server that you have needs Authentication, useDefaultCredentials parameter needs to be used which will use make the Request to Proxy server via Default Credentials of the logged in user.
Please note, currently UiPath does not support configurations where you need to make request to Proxy server with specific user. This is not yet supported.