highend theme no working with woocommerce

Hi,
I am trying to integrate wordpress-learndash and woocommerce to sell my online classes. However, it is impossible to work with them. The error is that when I select a product and click to the “Add to cart” button, the product is not showed in the cart page. I have been working with these providers, but they say that the error is coming from my theme. I bought the theme Highend. How Highend can resolve this problem? Thanks.

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