Carry on policy, Air Canada?

I’m traveling from SeaTac, layover in Vancouver Canada, then 15 hours to Brisbane, Australia. Both these flights are with Air Canada, then my flight from Brisbane to Christchurch is with Air New Zealand. I’m confused on if I’m allowed to bring a carry on and a personal item without checking anything. I’m flying economy. Since it’s international I should be able to right? The website information is just so confusing :(