ERROR: Peer certificate rejected | How do i accept the certificate ?

private void button1_Click(object sender, System.EventArgs e)
{
    SessionOptions sessionOptions = new SessionOptions
    {
        Protocol = Protocol.Ftp,
        HostName = "1.2.3.4",
        PortNumber = 990,
        UserName = "username",
        Password = "password",
        FtpSecure = FtpSecure.Implicit,  
    };
    using (Session session = new Session())
    {
        session.Open(sessionOptions);
        TransferOptions transferOptions = new TransferOptions();
        transferOptions.TransferMode = TransferMode.Binary;
        TransferOperationResult transferResult;
        transferResult =
            session.GetFiles("/BackupLogs/*", @"C:\InternalShortcuts\BackupLogs\", false, transferOptions);
        transferResult.Check();
        foreach (TransferEventArgs transfer in transferResult.Transfers)
        {
            Console.WriteLine("Download of {0} succeeded", transfer.FileName);
        }
    }
}

SessionOptions.TlsHostCertificateFingerprint

TlsHostCertificateFingerprint = "00:11:22:33:44:55:66:77:88:99:aa:bb:cc:dd:ee:ff:00:11:22:33"