Visual Studio setup an deployment projects require the target “bitness” of target Windows operating system to be set. This means that I have to create two installation files, one for 32bit and one for 64bit Windows for my Visio add-ins, for example.
The bitness of an individual Visio application can be checked from the File / Account / About Visio dialog, and similar screens are available in other Office applications:
64bit Windows users can install either 32bit or 64bit Microsoft Office, which will install the relevant Visio Viewer package. The installed edition of Visio should then match the installed edition of Office.
Any Visio add-in installations need to match the bitness of the installed Visio application.