WhatsApp E-commerce Order Send Button add-on is for sending order details in vendor WhatsApp , so vendor can be notified , also a copy of the order will be stored in your WhatsApp account too.
After completing the installation of the add-on, you just need to go to Ecommerce -> Select Your Store -> Appearance Settings ( from right-sided menus) menu.

For Lifetime premium member-only, here the tutorial on how to Activated All Xerochat Add On in Original Xerochat Script to bypass server code activation without effect your updated license.
This case for those who buy Original XeroChat but can not afford all add-on price.
You can use nulled xerochat add on without effect original main license code. Click here