"I must be honest, I am surprised," Ackermann told Radio Sport Breakfast.
"I've had the privilege of touring your wonderful country a lot of times and the one thing I know is New Zealanders are passionate about their rugby.
"You would think everybody would get behind the Crusaders. It's a surprise, but I suppose - you get it in South Africa as well - fans are so loyal for their provinces that they will shout for the opposition.
"For us, it's just such a privilege to host a quality side like the Crusaders and we're going to respect them for what they can do as a rugby team."
Ackerman admitted his side would have to defend better than they did against the Hurricanes, when they trailed 22-3 shortly before half-time, but rallied to win 44-29.
"The first two tries, we had control of the ball and lost the ball, but the third try was way too easy and we've spent a fair bit of time to rectify that," he said.
"In the finals, if you have too many of those moments, you're not going to get over the winning line.
"We were fortunate to get over the line on [Sunday], but the Crusaders will put sides away and you can't catch them ... or they come from behind to win the game, so you can't afford those mistakes."