I've setup a WhatsApp Business to test WhatsApp API for sending messages. I've followed the getting started guide, but when I send a test message from the main interface of WhatsApp API, the message is sent but is not received by the recipient, even though there is a template approved by Facebook

As shown in the pictures, when I press send message, the sending succeeds but the recipient receives nothing

update : i added a real number ( not using a facebook testing number ) also did not work

Meta has mentioned in the document that they could add 20 numbers under an Waba account I'm not able to add more than one number now.. Could anyone let me know how should I do that?
Kindly suggest me an idea to add multiple numbers

I noticed that when I sent a template message to an end user, I got a response as the message was sent, but the user gets a message after 1-2 min. I tried to send 10 messages to a number with high speed Internet and all messages are delayed without any reason. Is anything need to rectified from our side to deliver message without any delay?

how to create a carousel template in Facebook WhatsApp message template. i couldn't find the carousel type in the category tab.

getting this error while sending the message.