Encrypt WinSCP connection

Hi It's my first post I hardly used WinSCP.
We are sending file to client using WinSCP. Client is getting "There has been an error decrypting a file sent from your system". We checked with receiving side getting
"decrypt the file and cant (because its not encrypted)."
Dont have encryption option is settings.

- We shared PGP keys to encrypt but still same issue. Kinldy please provide the solution how can I encrypt the tunnel and send data securely. Usingh SFTP on Port 22

Thanks you so much

WinSCP SSH/SFTP connection is always encrypted.
Your client seems to require you to encrypt the transferred file itself (using PGP?), not to encrypt the connection (although that's implied by the use of SSH/SFTP connection).

Encrypting the file has nothing to do with WinSCP. If my understanding is correct, you need to use PGP to encrypt the file before you transfer it with WinSCP.