Blocked Plug-in in Safari 10.1
Without clicking the back button (or Command-[ ) of the browser:


Although the plugin is blocked, you can still use Command-S (or File > Save As) as well as File > Export as PDF to save the file to a folder.


Alternatively, click the back button (or Command-[ ), and then:


Option-click on the original link to download the file
Command-click opens the PDF in a new tab (PDF will not be blocked)
Ctrl-click yields the option "Download linked file as"