Microsoft Access 2016, 2013 and 2010 each have 32 and 64-bit versions. The 32 and 64-bit versions are two distinct programs and cannot both be installed on the same machine. Note that even though your Windows version may be 64-bit, you may have the 32-bit version of Microsoft Access installed.
While they appear the same from the user interface, the Access versions are different internally and require ActiveX controls, Windows API calls, library references, and other VBA code changes that are bit specific.
This also means that if you have users with different bitness versions of Access, you need to create separate copies of your database for 32 and 64 bit users. You will need to build them with separate 32 and 64-bit installations of Access, reference the appropriate libraries, and deploy them accordingly.
Since the performance gain in the 64-bit version of Access is fairly modest, we generally recommend using the 32-bit version to avoid incompatibilities.