The defender has discussed the trial conducting an Instagram Live interview on New Era Global Sports's page.
The Blues man said: "Yeah I went [to Man United] for a week, then I got injured and went back to Barnsley. It was in pre-season, the first team was away and I was just with the under-23s
"At the time, I wanted to go somewhere and feel like part of a first team. I felt like if I tried to go to one of the bigger clubs I would have been back into a U23s setup, which isn't what I wanted.
"I'd just played 20 games in League One at 18 years old, which obviously as a defender is good. So I felt like it would have been a step backwards to go to 23s football.
"I wanted to feel like I was going in to, not starting every week, but being in a first team setup."