I will give you a more broad vision of X.
X is indeed a unique theme in many aspects.
If you want to work with shortcodes, you can, in some cases, light the lightbox specifically it is necessary to use the shortcodes. Shortcodes can be inserted on WP Admin classic editor or using our page builder Cornerstone. On Cornerstone you would add shortcodes to RAW CODE ELEMENTS or TEXT ELEMENTS.
That said, when building your website with X, you dont need to use shortcodes really often as our page builder offer visual elements that can be assembled code free.
If you haven´t used Cornerstone yet, I do reccomend you to watch a couple of tutorials on our Knowledge Base and Youtube and start to work with it, it is a brilliant page builder that will allow you to build amazing layouts in blazing fast speed.
Here is the link to our Knowledge Base : https://theme.co/apex/forum/t/knowledge-base-overview/287
On this page you will find Cornerstone Tutorials and a list with all our shortcodes.
You dont need to install anything to have shortcodes working, you do need to have the plugin Cornerstone active, it will install itself, it is necessary that this plugin is active even if you decide to not use it.
When building sites with X I usually choose a demo to start from on WP Admin > X
After that I go to X > Theme Options to adjust the general styling of the website, like logo, button colors, trypogrphy etc...
And than I start to tweak the existing demo pages or build new ones with Cornerstone.
If you have further questions, please let us know