The Toon were always in control for the 3-2 victory, which saw them win their playoff tie 9-3 on aggregate.
Sandro Tonali struck the opener on Tuesday night and said: "It was obviously a great start, scoring two goals in the first six minutes. After that, it was a little too open.
"It was hard, because the (aggregate) score was 9-3, so it was difficult to continue (the way we started), but the most import thing is getting the win and getting through to the next round."
Toon defender Alex Murphy stated: "You don't really enjoy the start. The ball went over my head inside five seconds, but then once the game goes on, you start to enjoy it as you settle. You don't know how many Champions League games you'll play in your life, so you need to enjoy it."
Jacob Murphy also said: "It was job done. We had to come into today with a professional head. You could see the tie wasn't done till it was all over. We made hard work of it at times. We got off to a flying start. The damage was done there."