1st Step:-

Before adding this widget, make sure you have Fontawesome installed on your blog. 
If not, add this code before </head> or &lt;/head&gt;&lt;!--<head/>--&gt;

/* Fonts Awesome Code Start */
<script type='text/javascript'>//<![CDATA[//CSS Readyfunction loadCSS(e, t, n) { "use strict"; var i = window.document.createElement("link"); var o = t || window.document.getElementsByTagName("script")[0]; i.rel = "stylesheet"; i.href = e; i.media = "only x"; o.parentNode.insertBefore(i, o); setTimeout(function () { i.media = n || "all" }) }loadCSS("https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css");//]]></script>
/* End */

2nd Step:-

First open Blogger > Click the Themes Menu, Edit HTML and

Add this CSS Code before </head> or &lt;/head&gt;&lt;!--<head/>--&gt;

<style type='text/css'>/* Download Counter Box */#btnx{cursor:pointer;padding:10px 20px;border:0;border-radius:3px;background:#fff;color:#e67e22;float:right;text-transform:capitalize;font-weight:500;transition:all 0.5s}#btnx:hover,#downloadx:hover{background:#d35400;color:#fff;outline:none}.batas-downx{display:block;margin:0 auto;border-radius:4px}.dalam-downx{background:#e67e22;color:#fff;padding:20px;display:block;border-top-right-radius:3px;border-top-left-radius:3px}.file-info{color:#fff;display:inline-block;font-size:1.2em;line-height:38px;text-align:left}.catatan-downx{padding:20px;background:#f7f7f7;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:#555;font-size:14px}#downloadx{float:right}#downloadx{padding:10px 20px;border-radius:3px;background:#fff;color:#e67e22;float:right;text-align:center;font-size:14px;text-transform:capitalize}.bungkus-info span{display:inline-block;line-height:38px;float:right}.file-deskripsi{display:block}.file-deskripsi span{margin-right:3px}@media screen and (max-width:640px){.batas-downx{float:none;width:100%}}@media screen and (max-width:320px){.file-info{display:block;text-align:center}#btnx, a#downloadx{width:100%;margin-bottom:10px}.bungkus-info span{float:none;width:100%;text-align:center}.file-deskripsi{text-align:center}}</style>


3rd Step:-

After that add this code before </body> or it can also be added before </head>

<script type='text/javascript'>//<![CDATA[function generate(){var e,n=document.getElementById("downloadx"),t=document.getElementById("btnx"),a=document.getElementById("downloadx").href,l=10,d=document.createElement("span");n.parentNode.replaceChild(d,n),e=setInterval(function(){--l<0?(d.parentNode.replaceChild(n,d),clearInterval(e),window.location.replace(a),n.style.display="inline"):(d.innerHTML="<i class='fa fa-clock-o' aria-hidden='true'/> File siap diunduh dalam "+l.toString()+" Detik....",t.style.display="none")},1e3)}//]]></script>


Edit the writing on the code that is marked, also edit the l=10 number 10 means that the required retreat time is 10 seconds. 

Click the Save Theme button.

4th Step:-

Next to add the Download Box caller, add the code below in the post on the HTML tab.

<div class="batas-downx"><div class="dalam-downx"><div class="bungkus-info"><div class="file-info">Nama File</div><button onclick="generate()" id="btnx"><i class="fa fa-cloud-download" aria-hidden="true"></i> download</button><a id="downloadx" href="linkdownloadx" style="display:none"><i class="fa fa-cloud-download" aria-hidden="true"></i> download Ulang</a></div><div class="file-deskripsi"><span class="uploader"><i class="fa fa-user-circle" aria-hidden="true"></i> Namina Responsive Blogger</span> <span class="file-size"> <i class="fa fa-file" aria-hidden="true"></i> File Size 300MB</span></div></div><div class="catatan-downx">Jika tidak terdownload otomatis silakan klik download Ulang. Dan jika link rusak silakan lapor melalui halaman Contact Form blog ini.</div></div>