simply - it can't be done, you will need third party software
Depends whether you are trying to protect an existing PDF or a new PDF.
The free Acrobat Reader will not password protect existing PDFs ... unless you pay a monthly fee ($13-15 per month!)
For a
newly created PDF:
It can't be done from
Access
However, it
can be done from
Word.
Before saving a Word doc as a PDF, click
Options.
Then select '
Encrypt this document with a password'
Enter a password between 6 and 32 characters.
Job done!
This method does provide an
indirect way of protecting
existing PDFs
Open the
PDF in Word (2016).
Now
Save As ... and enter a new file name.
Add a password as before.
NOTE: Opening a PDF in Word 2016 is usually fine but may not give perfect results if the document is very complex.