[Theme: Book Your Travel] Integrate payment gateway

Hi, I would like anyone to help me with my theme as its developer as gone MIA on themeforest for some time now. Here’s a demo link to the theme. https://www.kajag.com/themes/book_your_travel_wordpress/

Its a very simple issue, we want to make online payments possible once anyone has made any form of booking, we want a situation where when once a user books by clicking the “order” button, him/her also gets to pay for the booking immediately.

The problem is the theme doesn’t use woocommerce rather it uses custom post taxonomies to create accommodation post types, location post types, tour post types and so on. So how do we integrate a payment gateway to integrate with the theme.

We won’t mind installing Woocommerce, but how do we make it integrate properly with the theme.

Please help. Thanks!