Open Google Chrome [ if not open already ]

Click on the 3 Dots on the top right corner.

Type: "pdf" in the search bar as shown below.
Click on Site Settings Arrow

Scroll all the way down in the page until you get to Additional Content Settings

Once open click on the arrow for PDF documents

Click on Download PDFs as shown below and then close the browser once it has been selected.
You should now download all pdf documents instead of downloading them.
Once downloaded you can open them with your default pdf viewer.