If you haven't gone through the prerequisites and the v2 structure, please have a look at 

This is an example how to fetch product from specific category. 

Category search

This parameter defines the type of request it is, which should be 'CATNAV' for category merchandising queries. There are other values available, detailed elsewhere in the documentation.

typeOfRequest

Specify the name of the category to retrieve results from, in the same case and format as it is indexed with Klevu.

For nested categories, use the ; character to separate the hierarchy. For example, for 'Mens > Shoes > Trainers and Sneakers' you would specify: Mens;Shoes;Trainers and Sneakers.

categoryPath

This is related to Klevu category Merchandising Webhook:
https://help.klevu.com/support/solutions/articles/5000892289-klevu-webhook-integration-guide
When a webhook for Category Merchandising is received, this field will be included in the request payload. Pass this field when some Merchandising rule is being updated and search-cache bypass is needed.

merchandisingVersion

Overview

Category Product Search

A/B Test

Storefront APIs

Introduction

Search as you type

Record search

Faceting

Advanced Filtering

Configurations

Personalisation

Examples

V1 (deprecated)

Smart Search

Smart Category Merchandising

Trending Products

New Arrivals

Similar Products

Customers Also Viewed

Customers Also Bought

Hand Picked

Visually Similar

Smart Recommendations

URL Redirects

Banners

No Results Customisations

Dashboard/KMC Settings

Klaviyo : Search Events

Klaviyo : Segmentation

Connectors

Initialization

Send a Message

Handle User Actions

Search Events

Category Events

Recommendations Events

Purchase Data

Add To Cart

UUID

Analytics Tracking

Guide