Customization (and theme installation) is not included in item support at Themeforest (and Codecanyon).
Please read the following page;
What is customization?
For example; Changing the color scheme, adding a new feature, changing the design, adding a plugin compatibility (for example; Woocommerce) etc.
We don’t provide customization services. If you need professional help with installation WordPress, setting up a WordPress theme, implementing a new feature or customizing a theme or a plugin, you can buy a service from Envato Studio with a small fee.