I don't think Huma used a State Dept. computer. Hillary didn't.
I think Huma Abedin was working in the State Department with a computer linked to Hillary’s restroom homebrew server. Any emails she received, were forwarded to her home laptop. It was a laptop because it could be easily hidden if there was a chance it was going to be confiscated by an investigation. Any emails she sent were also sent to her home laptop. This was an effort by her to have a duplicate copy of all correspondence. Was it to be used as blackmail? I am thinking it was.