无法将生成的pdf保存在我的远程服务器上

我正在尝试将生成的pdf保存在自定义文件夹中，但未保存。我想将pdf作为附件发送到电子邮件
中，这是我的代码生成并保存pdf

I am trying to save generated pdf in custom folder but its not saving. I want to pdf to send as attachment in email Here is my code generate and save pdf

public function email($timestamp=0, $load_id=0, $type=0){
    $this->load->library('tcpdf/Pdf');
    $pdf = new Pdf('P', 'mm', 'LETTER', true, 'UTF-8', false);
    $pdf->SetTitle('Document');
    $pdf->setPrintHeader(false);
    $pdf->setPrintFooter(false);
    $pdf->SetHeaderMargin(10);
    $pdf->SetLeftMargin(10);
    $pdf->SetRightMargin(10);
    $pdf->SetTopMargin(10);
    $pdf->SetAutoPageBreak(true, 25);
    $pdf->SetAuthor('Author');
    $pdf->SetDisplayMode('real', 'default');
    $pdf->Write(5, 'Cal Sierra Load Document'); // add a page
    $pdf->AddPage();
    //         $carriers = $this->admin_model->getCarriers(array(), array(), 0,0,1,"","","",1);
    $load=$this->admin_model->getLoad($load_id);
    $pickupDrops=$this->admin_model->getPickupDrops(0,0,1,0,$load_id);
    $loadPickups=array();
    $loadDrops=array();
    if(!empty($pickupDrops)){
        foreach($pickupDrops as $row){
            if($row['type']==1)
                $loadPickups[]=$row;
                else
                    $loadDrops[]=$row;
        }
    }

    $data['load'] = $load;
    $data['loadPickups'] = $loadPickups;
    $data['loadDrops'] = $loadDrops;
    //         $data['carriers'] = $carriers;
    $data['settings'] = $this->settings_model->getSettingsFile();
    $data['currentTime'] =  $timestamp;

    //         echo "<pre>";
    //         print_r($data);
    //         exit();

    switch ($type) {
        case 1:
            $html = $this->load->view('documents/doc1', $data, true);
            break;
        case 2:
            $html = $this->load->view('documents/doc2', $data, true);
            break;
        case 3:
            $html = $this->load->view('documents/doc3', $data, true);
            break;
        default:
    }

    $pdf->Output('custom'.'Document.pdf', 'F');
    $this->Output("custom");

    exit();
}

我不确定将文件夹保存为pdf的位置，同时也添加了我的文件夹布局图片 https://i.stack.imgur.com/tUadw.png

I am not sure where put my folder to pdf i am also adding my folder layout picture https://i.stack.imgur.com/tUadw.png