To open / access a "Windows" PDF from a Mac - Here are two avenues to try (either should work):
Click the PDF file's icon in the Finder to select it. Choose File > Get Info. Click the triangle next to Open With, and choose Adobe Acrobat Reader or Adobe Acrobat from the pop-up list (if your preference is not on the list, choose Other to select it). Click Change All.
Can I open Windows files on a Mac?
You can open them using Microsoft Word on Mac, if you have purchased Microsoft Office for Mac. You can also open them in Pages if you have iWork. If you have neither Word or Pages, your easiest option is to open them in the free TextEdit program that comes with your Mac.