End Note stands in between the places you find citations and your Word document.
It stores and lets you sort and organize your citations, and holds other descriptive information and files (such as pdfs) associated with those citations.
You can save records and pdfs in End Note Web and sync them with your main End Note library.
Starting from August 22, 2016, Office 2016 for Mac users will all eventually be upgraded to a 64-bit version from the 32-bit version.
These popular add-ins are known to cause problems with Office 2016 for Mac 64-bit if you have the 32-bit version installed.