They have provided me with necessary server details, username/password (they require dual authentication with cert first, then username/password) and both SSL cert and server cert. These certs are provided as .cer's and contain only the cert/public key within them, with the format "----BEGIN CERTIFICATE----....<cert-info>.....----END CERTIFICATE----"
It's my understanding that this format is actually the .pem format (which is required by WinSCP) so renaming and using their provided SSL cert should work fine.
However, when supply either certificate in the "Client Certificate File" returns the error, "error:0906D06C:PEM routines:PEM_read_bio:no start line". I have tried changing format to UTF-8, UTF-8 BOM, and ANSI but the error persists.
What am I missing? Did my client provide bad certs perhaps? Thank you for all your help and excuse my ignorance on this subject. Most information out there boils down to "just use SFTP!" which isn't helpful.