Message sent but not delivered in whatsapp PHP API

Question

I am using whats app API https://github.com/venomous0x/WhatsAPI

But When I am trying to send message with this api

Then I am getting the status {"success":true,"data":"Message Sent!","messages":null}

But the message is not delivered to inbox

I have tried with number without 0 or country code, with 0 and with country code

But not delivered the message