After installing the app and activating it with the Pixel code you've got from your TikTok Business account, the app will automatically trigger E-Commerce events when the following actions will be performed in your store by your customers:
Product Details Page View - An event that will be triggered whenever a customer is viewing a certain product page.
Add To Cart - An event that will be triggered when the "Add to Cart" button in products pages will be clicked.
Place an Order - An event that will be triggered when the "Checkout" button will be clicked.
Payment Complete - An event that will be triggered when the customer will reach either the post-purchase "Thank you" page, or the post-purchase offers page (if you have one).
Because the app is automatically triggering these events, you don't have to manually configure them in your TikTok Business account. You just have to choose E-Commerce events when you create the Pixel for the first time.