A separate version of diCrPKI.dll is provided which is compiled for X64 platforms.
Both the 32-bit and the 64-bit DLLs are installed by the setup on a 64-bit platform.
Wow64 (Windows-on-Windows 64-bit) will find and use the correct one it needs.
Please refer to our web page Using CryptoSys PKI Pro on a 64-bit system for more details.
The .NET Library DLL is compiled for both 32- and 64-bit platforms. When compiling your .NET project in MS Visual Studio, make sure you set Solution Platforms to Any CPU.