Hi,
In the posting What target bit setting should I use to compile ZOS-API extensions? | Zemax Community Ethan sets out a great point. Sadly that post is closed for further replies so I’m starting a new thread for replies 
I’d strongly recommend that only x64 executables be used with OpticStudio. OS was 64 bit from its earliest days on Windows 3.1, and users from back then will remember having to install the 64-bit extensions for 32-bit Windows 3.1 via floppy disk. The Operating System has been 64 bit natively since Windows 95 and NT 4.
The reason Zemax is 64 bit is to prevent cumulative errors when tracing from surface to surface. Using 32-bit means you can run out of precision with big systems when trying to keep track of sub-wavelength OPD errors.
As long as your code is only analysing data produced by OpticStudio, 32 bit might be OK, but I’d seriously avoid using 32 bit as it’s asking for trouble to mix 32 and 64 bit executables. Keep all extensions 64 bit unless you have a compelling reason to do otherwise. 32-bit being the default setting is not a ‘compelling reason’ IMHO
Keep it 64-bit!
