The terms 32-bit and 64-bit describe how much information the computer's processor can process in a unit of time. The 64-bit version of Windows can handle a larger and more effective amount of random access memory (RAM) than 32-bit systems. This difference can also affect the compatibility of the software you download.
Luckily for you, PDF Reader Pro Windows supports both 32-bit and 64-bit. They are both combined in one installation package. When you install the software, the appropriate number of digits is selected automatically according to the system during installation.
Go download the app here to test first.