How can I add a third-party discount field widget to a checkout page?

Hi can anyone help to remove shopify oringinal discount field and add a third-party discount field widget to the desktop&mobile checkout page?(theme Dawn)

widget code is

(provided by app)

URL:Hannah’s Accessory|韓國飾品|18K金|92.5 (hannahsaccesory.myshopify.com)

PASSWORD:naihia

You can change the look and feel of the subscription widget by adding CSS rules to your Shopify theme. This article will explain how to add custom styling to the widget.

  1. Edit your Shopify theme
    Navigate to your Shopify store and in the theme editor, open the theme code

  2. Adding custom styles to CSS file
    Click on the Assets folder and select theme.css.liquid. This is where you’ll add custom CSS. Then paste custom styles at the bottom of the CSS file

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