download_button.md

1. Install the Media Entity Download module.
   • composer require drupal/media_entity_download
2. Create a FileDownloadLink field formatter:
   • either use an existing custom module on your site or create a new one
   • create a file at whatever_module/src/Plugin/Field/FieldFormatter/FileDownloadLink.php
   • paste in the contents of the attached FileDownloadLink.php
3. In the GUI create a paragraph that has two fields:
   1. a Media Library reference field: file_from_media_library
   2. a short plain text field: button_text
4. Set the display for the media file to File Download Link
5. Put an instance of that paragraph on some node, so you can grab the name of the paragraph template.
6. Create a paragraph template. In it put:

{% extends 'paragraph.html.twig' %}

{% block content %}
  {% set link = content.field_file_from_media_library[0]['#plain_text'] %}
  {% set label = content.field_button_text['#items'].value %}

  <a href="{{ link }}" class="button">{{ label }}</a>
{% endblock content %}

FileDownloadLink.php

<?php

namespace Drupal\prc_helper\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Field\FormatterBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\media\Entity\Media;

/**
 * Plugin implementation of the 'file_download_link' formatter.
 *
 * This formatter requires the Media Entity Download module.
 *
 * @FieldFormatter(
 *   id = "file_download_link",
 *   label = @Translation("File Download Link"),
 *   field_types = {
 *     "entity_reference"
 *   }
 * )
 */
class FileDownloadLink extends FormatterBase {

  /**
   * {@inheritdoc}
   */
  public function viewElements(FieldItemListInterface $items, $langcode) {
    $elements = [];

    foreach ($items as $delta => $item) {
      // Load the media entity from the entity reference.
      // We're checking that it's actually a media item.
      if ($media = Media::load($item->target_id)) {
        // This depends on the Media Entity Download module
        $url = '/media/' . $item->target_id . '/download';
        $elements[$delta] = [
          '#plain_text' => $url,
        ];
      }
    }

    return $elements;
  }

  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, FormStateInterface $form_state) {
    $elements = parent::settingsForm($form, $form_state);

    // Add any additional settings form elements here if needed.

    return $elements;
  }

  /**
   * {@inheritdoc}
   */
  public function settingsSummary() {
    $summary = [];

    // Add any additional settings summary here if needed.

    return $summary;
  }
}