This is a web application.
So did you use the credentials of the local windows account that runs your web server for the
Anyway, WinSCP .NET assembly is not designed for use from a web server. See:
... it is also difficult to use the assembly within a restricted environment like a web server, that limits or even restricts execution of external processes.
Having that said, most users are able to use the assembly even from a web server. I do not know what's specific about your setup.