Like Alberto Ravasio wrote, OS X contains an option to output anything you see as PDF.
See
Preview (Yosemite): Print PDFs and images
So for example, if you are doing research and see an article on Wikipedia that you want to save, you go to the File menu in Safari and select Export as PDF, give it a name, and a location on your drive. You can then open those documents with Preview or with Adobe Reader.
Similarly, if you use Pages or Numbers or Excel or Word, you can send the output to a PDF file, similar as if you were printing it. So no, you don't need a PDF writer.
I am looking to install a PDF writer so I can capture documents and save them to a customer file. Is there an Apple function for this or do I need to install a PDF program?
But if you are looking for screen scrapers or data collectors, that is something else.
This PDF ability in OS X is a major advantage the Mac has had over the years. It is often forgotten as to how well it really works and how flexible, along with Preview, it works.