Hi,
It depends on how your theme is constructed, or if you use any page builders as well.
– If you use a page builder plugin/integrated, then try adding a new HTML block, where you can place the search box shortcode
– You can also use a search widget, on any of the widgetized areas
– The search shortcode can be used within the theme files as well, however I suggest contacting the theme author to help you locate the corresponding theme files and where to replace them
– There is also a possibility to use the plugin as a menu item if needed
I hope this helps!