This template is using Magnific Popup to show a lightbox. You can customize it using the options here : Magnific popup Options
Anytime you click on a link going to an anchor link on the same page, use this function to have a smooth scroll effect.
Configuration:
<div id="targetDiv">content</div>
<a href="#targetDiv" class="smoothScroll">Click here to go the target Div</a>
smoothScroll("#targetDiv");
This function is used in Gallery 2. You can use the documentation here
Slick Carousel is used in Gallery 4. You can use the documentation here.
If you need to personalize it more, you can use the official documentation here.