TransferOperationResult operationResult = 
    _oSession.GetFilesToDirectory(
       sFtppath,
       sNetpath,
       options: transferOptions);

var sFtppath = "./Solutions/Inbound/";
var sNetpath = @"\\Solutions\Inbound\";
...
using (_oSession)
{
    TransferOptions transferOptions = new TransferOptions
    {
        FileMask = "*.txt",
        TransferMode = TransferMode.Automatic
    };
 
    try
    {
        TransferOperationResult operationResult = 
            _oSession.GetFiles(
               sFtppath,
               sNetpath + "*",
               false,
               transferOptions);
 
        operationResult.Check();
 
        foreach(TransferEventArgs transfer in operationResult.Transfers)
        {                       
            var tmp = transfer.FileName;
            _oSession.MoveFile(tmp, tmp + ".processed");
        }
...

sNetpath = @"\\Solutions\Inbound\"