Is Nitro PDF Professional (188.8.131.52) compatible with Windows 10?
Nitro PDF Professional reached version 10. In no way the version you mentioned is compatible with Windows 10. I strongly advise getting the latest version in order to enjoy all the features of the application. Version 6 is old and lacks various functionality, that's why is recommended to avoid it. Use the link posted below to download it.
The trial version will last 14 days after which requires purchasing: http://install.nitropdf.com/pro10/en/retail/nitro_pro10_x64.exe