WinSCPnet.dllfor 32-bit .NET framework, even on 64-bit system.
As the instructions for registering the WinSCP .NET assembly for COM shows, on 64-bit system, you generally need to register the assembly both for 32-bit and 64-bit:
%WINDIR%\Microsoft.NET\Framework64\v4.0.30319\RegAsm.exe WinSCPnet.dll /codebase /tlb:WinSCPnet64.tlb
Do not add the
.tblmanually to Excel. The assembly appears itself after being registered correctly.