"I was super-stoked just to be there though. There was a lot of pressure in the semifinal but I put down a good run and managed to get through, so everything from then on was a bonus," Zack said.
Double Olympian Mike Dawson's 10th in 2004 and Tauranga kayaker Callum Gilbert's eighth in 2014 are the only other two times a Kiwi has made a junior world championship K1 final and Zack was delighted to join the vaunted pair, who are both classy senior paddlers now.
Zack still has one more year in the junior ranks, which gives him plenty of confidence moving forward.
"Making the final has been a goal for a very long time now so I'm happy to complete that and I couldn't stop smiling on the start line.
"I guess there's disappointment I wasn't able to perform how I wanted to but I've still got next year and I know I'm good enough to compete with these guys now too."
Emphasising how tough the course was, no paddler went clean in the final, while Zack was one of only three non-European paddlers heading off United States duo Tyler Smith and Joshua Joseph.
The European dominance continued in the under-23 division too where Gilbert and Finn Butcher both exited in the semifinals after missing gates and incurring 50 second penalties.
Butcher's 93.07 second raw time would've qualified him in sixth but the 56 seconds worth of penalties dropped him 29 places to 35th, two spots behind Gilbert.
"Once again, I was feeling really good in the boat but I hit gate seven with the very front of my boat and it swung around me.
"It was an unlucky swing of the pole but I wasn't quite accurate enough on getting through the poles in the first place.
"Despite that, I actually had quite a fun run, the course was flowing a lot more than the heats and with a couple of spins in it, was a bit trickier," Butcher said.
Gilbert came unstuck on gate 11 and added a touch on gate 15 to pick up 52 seconds in penalties.
"Gate 11 was a tight upstream and I thought I was in but after looking at the video, it's clear I was too tight.
"Other than that and another small mistake, the run was pretty good," Gilbert said.
Slovakia's Jakub Grigar landed an emotional home-town win, with the defending under-23 world champion and two-time world junior champion smashing the under-23 final in 89.86 seconds, almost two seconds clear of Austria's Mario Leitner in 91.89, with France's Mathieu Desnos third in 93.51.
Butcher and Gilbert will now return home to prepare for September's senior world championships in France and the rest of the ICF World Cup series.
"It's still early in the season and the big goal is at the end - there's so much to learn from this race and work on at home to prepare for the worlds in Pau," Butcher said.