This plugin was created to allow readers to download music that has been uploaded to a blog from a single page.
The plugin looks through the posts table in the wordpress database for all attachments that have a mime type of audio/*. It displays this when the reader looks at a page ( not a post ) named ‘Downloads’. The reader can then select the songs they wish to download, click on “Download All Selected” and download a zip file of all of the files selected, or they can simply download the single song they wish to listen to. The list also lets users view the attachment page for a particular song, letting them leave comments.

DownloadMusic

Plugin to list all audio files uploaded to a blog, and let users download them in a zip file.

eugenealegiojo

The plugin that will let admin user to add download links to any posts/pages in simplest way and hassle free. 
Allows all your site visitors to download any files from your website without any user restriction.
<h4>Features</h4>
<ul>
<li>Downloader button is available in your admin content editor for post, page or post type. Shortcode will be generated automatically.</li>
<li>Insert download links manually via shortcode [media-downloader] to any posts, pages or custom post types. Check for more parameters below (Embedding).</li>
<li>Allow users to directly download in all file formats for free.</li>
<li>No file size limit for downloads. 
For more information please check the <a href="http://phplugins.softanalyzer.com/simple-file-downloader/" rel="nofollow ugc">Simple File Downloader</a> documentation page</li>
</ul>
<h4>Embedding / generated Shortcodes</h4>
Create a new post/page and click the ‘Add Download’ button from the content editor, then generate the shortcode below:
<pre><code>[media-downloader media_id="9" texts="Download Now!"]
</code></pre>
Media id is automatically added from your media library.
Here are the all the available parameters when generating shortcode for file download:
texts
If you choose to leave the texts parameter empty, then it be defaulted to ‘Download File’.
image_url
You can also use image/button as your download link. If you supplied this parameter, then texts parameter will be replaced by this image.
<pre><code>[media-downloader media_id="9" image_url="http://domain.com/wp-content/themes/images/button.png"]
</code></pre>
class
You can add class to your download link either a texts or image button. This is useful if you want to apply your own style.
<pre><code>[media-downloader media_id="9" texts="Download PDF" class="download-pdf"]
</code></pre>
display_filesize
You also have an option to display the size of the file. Just set it to ‘yes’
<pre><code>[media-downloader media_id="9" texts="Download PDF" display_filesize="yes"]
</code></pre>

Simple File Downloader

Simplest way to add download links into your posts/pages.

DownloadMusic vs Simple File Downloader