SilverD442, go to the menu where you want to add the menu option, click NEW.
From there, click SELECT under MENU ITEM TYPE, Scroll down to HikaShop section and select CATEGORIES LISTING.
Give the menu a name and click SAVE (not SAVE & CLOSE). Once saved, you'll see USER TOOLS - HIKASHOP OPTIONS.
Click HIKASHOP OPTIONS. There will be an alert that says it can do it for you. Go ahead and click it. Once done, you can click SELECT next to ASSOCIATED CATEGORY and pick the category you want that menu option linked to. You can customize further but, at this point, you can click the SAVE button, then click JOOMLA MENU OPTIONS (to return back to the menu option) and finally click SAVE & CLOSE.
Hope this helps.