Where are local pdf files stored on my Android tablet?

I use my tablet for work related instruction manuals. Everytime a file has been opened with my Amazon Fire tablet over the years, the Acrobat Reader says "Adobe Acrobat will create a local copy of this document."

How can I locate & copy these local files?

If I open the application on my tablet, it says the local location is:

"/data/user/0/com.adobe.reader/files/Downloads"

...but this location doesn't seem to exist.

I've seen alot of similar questions from frustrated people, but I haven't seen a good answer. Is there one?