For more information see: Should I install the 32-bit or 64-bit version of Office/Outlook?Note: Even when you are using the 32-bit edition of Office 2016, some add-ins might not be compatible yet with Office 2016.When you start Outlook for the first time after the upgrade, the startup could take some time.This is because your previous settings are being migrated.It of course never hurts to make a backup of your Outlook data first.If you are having difficulties removing your current version of Office via Control Panel, you can use the Fix It from the Microsoft KB article below which matches with the version that you wish to uninstall: When you are currently using an Office 365 installation of Office 2013, then upgrading to Office 2016 is going to be really easy as it will be offered as a regular update.By default, it will install the 32-bit edition unless you specifically tell it not to.If the 32-bit edition is what you want (again; this is recommended), then just follow the setup instructions and move to the next section in this guide.
The setup process is further the same as for the 32-bit version of Office.
If you want to install the 64-bit edition, keep reading…In order to install the 64-bit edition of Office 2016, you’ll first need to uninstall all 32-bit Office applications, including older versions.
If any such application is still installed, you will not be able to install the 64-bit edition of Office.
However, when you have a 64-bit edition of Windows and you know that all your add-ins and other applications that rely on Office support the 64-bit edition of Office 2016, you can safely install the 64-bit edition.
When it comes to Outlook, there is no direct benefit of having the 64-bit edition instead of the 32-bit edition.