Add shortcode to main menu with do_shortcode (Ajax Search Pro)

Hi!
I’m trying to change the search function by removing the default search and using Ajax Search Pro. In the plugin there is an option to “Replace the default theme search”, which I tried with decent result. When I click the magnifying glass it opens plugin search. With CSS I removed the icon and added the text “Offices”. Problem is that this solution is not responsive (when using smaller resolutions the “Office” -text ends up behind logotype, rather than being a part of burger-menu) and differ from the other menu items (no separator)
Preferably I’d like the search to be part of the menu (no icon, only text).

On the plugin documentation it says:

“To place the shortcode to the theme you need to find the proper location first. If you are not familiar with theme structures, I suggest you consult a developer before editing anything.
After finding the proper location, you need to place the theme shortcodes there. The difference is, that a theme shortcode is actually a PHP code block. You can find these shortcodes on the same place as the regular ones, on the search settings panel:”

The shortcode mentioned is:
<?php echo do_shortcode(‘[wpdreams_ajaxsearchpro id=1]’); ?>

Before I mess up too much myself (I’ve been trying for a good couple of hours) I’d like to know where I should place the do_shortcode-string.

Any help is appreciated!