Barnsley has several good opportunities against the Red Devils, but Robins admits they were not clinical enough in front of goal.
“We were on the back foot to start with I felt,” he said.
“Mentally, when you come up against Manchester United you probably give them too much respect and we were on the back foot because we conceded an early goal from a set piece.
“But they’ve got quality everywhere, whichever side they put out, but I just felt there was more in us.
“If you look at the stats we had 17 efforts on goal and you’d be hard pressed to find any side that creates that many chances against a Manchester United side.
“On a downside we haven’t taken any and you’ve got to take your chances.”
Robins added: “United had four or five chances on the night and scored the two. They had plenty of possession, but we defended well, I just felt we were lacking that bit of belief.
“There’s more in there for us. There’s more in the players, so there are positives.”