Here you can set the churn window in number of days and by saving it. So if a user does not make a purchase for a particular number of days, will be called a churned customer.
You can set the time for abandoned cart, so if a user adds items to his cart but does not check out for a particular time, then the cart is said to be abandoned.
You can also set the number of days for Lost cart, which means if a user does not check out for a particular number of days, after adding the items to his cart then the cart is said to be a lost cart.
See image of the process for better understanding.
Customer Churn Window: