You can get a free trial download on the Adobe website but after 30 days you will have to pay to use some features.
However, there are lots of free Adobe alternatives out there that you might just end up using for a long time if you give them a try.
I was skeptical about going to other PDF viewers and editors but after trying out a few I've been using Skim for the past 3 or so years. I recommend it to anyone who wants full PDF capabilities on their Mac laptop or computer.
PDF Escape is perfect for projects that you can attend to right in your web browser. I love to use web apps like this because they are quick and efficient and great for on the go updates or last minute edits.
Cute PDF is another free editor to download that is well-known and trusted. There is an online app to check out too. For businesses and people who edit PDF's regularly then Cute PDF Professional might be better. It has enhanced capabilities and does much of what Adobe Acrobat does with a much cheaper price tag. Try it free for 30 days then decide if its worth your while.