meta_key and array key

I want to send order tracking information to customer via whatsapp and i am using wpnotif for sending sms and whatsapp message

.In wpnotif the placeholder for some plugins are available but for your plugin, the placeholder is not available.

In such a situation wpnotif allows to make custom place holder and for making the custom placeholder need the meta_key and array key.

Please check this link for custom placeholder

https://help.unitedover.com/wpnotif/kb/how-to-create-custom-placeholders/