Don't use &
The purpose of "&" is to say "I want to do something else at the same time". If all you are wanting to do is one thing, you don't need to use the &.
Also, note that in general you CANNOT do anything that requires user input using WinSCP. If you really need to, use putty or another ssh client.
Also, note that in general you CANNOT do anything that requires user input using WinSCP. If you really need to, use putty or another ssh client.