Goals in the last 14 minutes from Bojan Miovski and Nicky Devlin gave the Dons an excellent platform to reach the group stages when they host the Swedish champions next Thursday night.
Aberdeen were well worth their 2-2 play-off first-leg draw and substitute Jamie McGrath had a debut goal ruled out for offside after the hosts were reduced to 10 men in stoppage-time in Gothenburg.
The Dons created chances throughout the game and were eventually rewarded for a bold approach.
Robson told RedTV: “First and foremost people need to realise they are a proper football team. I knew they were, I could tell by the players they moved on for a couple of million quid, and I know they have a very strong budget as well. I knew it was going to be a very difficult game for us.
“You could see us really pressing aggressively high and they are a really good side who can release the ball and get through you at times, and they did. We stayed brave with it and I thought the difference between the two halves was, when we get the pressing side right and actually started to handle the ball better…
“That’s what I said to them at half-time, all the things we work on every day with the ball, when they did that, and brought the two together, Hacken really struggled with us. We looked like a proper outfit.”
Robson added: “We are a work in progress but you can see the way we want to be and the speed we want to bring to the game, and the excitement. We were maybe a bit gung-ho and dangerous at times but I would rather do that than sit in.”