Determining whether a Pdf is accessible or not can be confusing.  You can run the built in accessibility checker in Adobe Acrobat Pro to see all the errors, but that doesn’t give a straightforward answer.  However, a European non-profit has a free piece of software , for Windows machines, which can help.  If you goto the Access for all website and fill out your name and email address you can download the software.   With a simple drag and drop the software can give you a green, yellow, or red to let you know very quickly if the document is accessible, needs some work, or needs lots of work to make it accessible.