WinSCP 5.2.1 dll and exe that could work with our application compiled on .net 2.0 webforms

We have a legacy application that used WinSCP DLL (version 5.5.2) to write files to SFTP servers.
One of the server got upgraded and now due to enhanced security protocol WinSCP 5.5.2 could not write to that server.

We used 5.21.0 in standalone executable mode and that was able to write to new server.

The problem now is if I replace the exe and dll in my product it shows incompatibility issues.

BadImageFormatException: Could not load file or assembly 'WinSCPnet' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded

Any idea how an I get the .NET 2.0 compiled version of WinSCP 5.21.0?

You can grab .NET assembly code and compile it yourself.
Or try using WinSCP 5.13.9, what is the last version targeting .NET 2.0.