This website uses PDF files.  Due to security concerns, browser developers have removed and are continuing to remove certain functionalities.  Reading a PDF file in the browser has been removed. The PDF file must be opened in Adobe Acrobat Reader, https://get.adobe.com/reader/.   In the past, when you click on a PDF file, the browser would start a small program inside the browser to view the file.  Now, the browser must be configured to open the file in a separate Adobe Acrobat Reader program.  You may need to change the behavior of your browser.  Below are links that may help resolve your issue.

http://www.howtogeek.com/237512/how-to-change-the-default-pdf-reader-in-windows-10/

https://www.google.com/search?q=setting+pdf+to+read+in+application&ie=&oe=#q=setting+default+pdf+viewer+in+windows

Microsoft has 2 browsers, Internet Explore ( the one we are used to ) and Microsoft Edge.  Visit https://www.google.com/search?q=start+IE+in+windows+10&ie=&oe=#q=start+IE+in+windows+10&start=10https://www.google.com/search?q=start+IE+in+windows+10&ie=&oe=#q=start+IE+in+windows+10&start=10