PDF and Word documents are often not formatted to meet ADA guidelines for accessibility.
Test for PDF Accessibility
Your PDF document must be tested annually to determine if it is accessible. You can do this with tools like PAVE.
To correct the issue, open the original document in Word and ensure that all of your images have alt text added and that your document is formatted and organized with proper headings.
Create Accessible PDF's
When creating a PDF, make sure that the PDF is created to be accessible by adding alt text and by formatting the document with proper headings.
Resources for creating accessible documents
Microsoft Word: How to create accessible PDFs in Word
Adobe Acrobat: How to create accessible PDFs in Adobe Acrobat