Conditions.php

<?php
namespace Astound\Affirm\Block\Adminhtml\Rule\Edit\Tab;

use Magento\Backend\Block\Widget\Form\Generic;
use Magento\Backend\Block\Widget\Tab\TabInterface;

class Conditions extends Generic implements TabInterface
{
    protected $_rendererFieldset;
    protected $_conditions;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Framework\Registry $registry,
        \Magento\Framework\Data\FormFactory $formFactory,
        \Magento\Rule\Block\Conditions $conditions,
        \Magento\Backend\Block\Widget\Form\Renderer\Fieldset $rendererFieldset,
        array $data
    ) {
        $this->_rendererFieldset = $rendererFieldset;
        $this->_conditions = $conditions;
        parent::__construct($context, $registry, $formFactory, $data);
    }

    public function getTabLabel()
    {
        return __('Conditions');
    }

    public function getTabTitle()
    {
        return __('Conditions');
    }

    public function canShowTab()
    {
        return true;
    }

    public function isHidden()
    {
        return false;
    }

    protected function _prepareForm()
    {
        $model = $this->_coreRegistry->registry('affirm_payment_restriction_rule');
        $om = \Magento\Framework\App\ObjectManager::getInstance();
        $hlp = $om->get('Astound\Affirm\Helper\Data');

        $form = $this->_formFactory->create();
        
        $renderer = $this->_rendererFieldset->setTemplate(
            'Magento_CatalogRule::promo/fieldset.phtml'
        )->setNewChildUrl(
            $this->getUrl('*/*/newConditionHtml/form/rule_conditions_fieldset')
        );

        $fieldset = $form->addFieldset(
            'rule_conditions_fieldset',
            [
                'legend' => __(
                    'Apply the rule only if the following conditions are met (leave blank for all products).'
                )
            ]
        )->setRenderer(
            $renderer
        );

        $fieldset->addField(
            'conditions',
            'text',
            ['name' => 'conditions', 'label' => __('Conditions'), 'title' => __('Conditions')]
        )->setRule(
            $model
        )->setRenderer(
            $this->_conditions
        );
        
        $form->setValues($model->getData());
        $form->addValues(['id'=>$model->getId()]);
        $this->setForm($form);
        return parent::_prepareForm();
    }
}