Trying to add a custom link to the CMS menu in SS4

config.yml

---
Name: paypalautosellerconfig
---

SilverStripe\Admin\LeftAndMain:
  extensions:
    - Sitelease\PaypalAutoSeller\Extensions\ProductWorkflowCMSMenuExtension

ProductWorkflowCMSMenuExtension.php

<?php

namespace Sitelease\PaypalAutoSeller\Extensions;

use SilverStripe\Admin\CMSMenu;
use SilverStripe\Admin\LeftAndMainExtension;

class ProductWorkflowCMSMenuExtension extends LeftAndMainExtension
{

    public function init()
    {
        // unique identifier for this item. Will have an ID of Menu-$ID
        $id = 'ProductWorkflow';

        // your 'nice' title
        $title = 'Product Workflow';

        // the link you want to item to go to
        $link = 'http://upsales.devserver.localdomain/admin/email-offer-tracking/Sitelease-PaypalAutoSeller-Model-Offer/EditForm/field/Sitelease-PaypalAutoSeller-Model-Offer/item/new';

        // priority controls the ordering of the link in the stack. The
        // lower the number, the lower in the list
        $priority = 3;

        // Add your own attributes onto the link. In our case, we want to
        // open the link in a new window (not the original)
        $attributes = [
            'title' => 'Open the product creation workflow'
        ];

        CMSMenu::add_link($id, $title, $link, $priority, $attributes);
    }
}