Getting from Airport to Zihua - options

After you clear customs there's a taxi table inside the airport to the right of the main door leading to the sidewalk. Purchase a ticket there for the collectivo. Take that ticket to the outside sidewalk to the taxi attendant at a podium. You can tell you are headed in the right direction by all the activity there. That guy will tell you that the collectivo will not leave until it's filled which he will tell you will take about 45 minutes. A couple of times I got lucky and got an immediate ride as a single in a Lincoln towncar direct to my hotel in Z, the second time I was one person that just happened to catch the last seat in a van that was almost full. The price is right but usually the wait is way too long and I return to the taxi table to exchange the collectivo for a taxi ticket--the ticket people are very understanding and will allow you the exchange if you pay the difference in price. So, as you can tell, getting the collectivo in a timely manner is a crapshoot.
An option is to ask the tourists waiting for their bags in the baggage area if they want to split a taxi ride with you. That has worked for me about half the time and it will save you the expense of paying it all yourself.