Go to Snapwidget and create an account. Click on "Get a free widget" > "Create a free widget" > select "Instagram Grid" > "Click here to update username" > log in with your account.
Configure the settings like this:
Thumbnail Size: 250
Layout (Columns X Rows): 4 x 1
Photo Padding: 15
Hover Effect: Fade Out
Sharing Buttons: No
Responsive: Yes
Copy the generated code > go to your blog dashboard > Layout > open the "Instagram" widget from the After Footer widget area > paste the code inside.
HOW TO SET UP THE WIDGET ON MOBILE LIKE THE DEMO?
The demo has two widgets - one for desktop (4x1) and one for mobile (2x2), since using the 6x1 widget everywhere means the images on mobile will be very small.To add a mobile widget, too, generate another Instagram widget and configure all the settings the same way, except for Layout (Columns X Rows) - it should be 2 x 2 instead of 4 x 1.
Copy the generated code > go to your blog dashboard > Layout > open the "Instagram" widget from the FOOTER8 widget area > use the HTML below and insert the widgets between the classes:
<div id="instafeed_wrap">
<div id="instafeed_link">Instagram <i>follow <a href="LINK" target="_blank">@yourusername</a></i></div>
<div style="clear: both;"></div>
<div class="instagram-desktop">
<!-- add the desktop Instagram widget here -->
</div>
<div class="instagram-mobile">
<!-- add the mobile Instagram widget here -->
</div>
<div style="clear: both;"></div>
</div>