Task: WhatsApp Webhook Callback URL Setup

n8n workflow:
{"id":"21","meta":{"instanceId":"057bb085b7b12e5ec63364c07c90a6991ff38e80cb982cf713e98103021c1136"},"name":"whatssapp webhook","tags":[],"nodes":[{"id":"6bf1cb65-5cb3-4bc2-a377-02b17fd104f1","name":"Webhook","type":"n8n-nodes-base.webhook","position":[880,420],"webhookId":"c507e282-9f2e-4542-aef2-29f6f9d50ee8","parameters":{"path":"whatsapp","options":{},"responseMode":"responseNode"},"typeVersion":1},{"id":"460df56c-144e-453f-9634-2717bd35ffcb","name":"Set","type":"n8n-nodes-base.set","position":[1260,420],"parameters":{"values":{"string":[{"name":"data","value":"={{$node[\"Webhook\"].json[\"query\"][\"hub.challenge\"]}}"}]},"options":{},"keepOnlySet":true},"typeVersion":1},{"id":"c6817745-b6aa-45a0-9456-dcd7720dba09","name":"IF","type":"n8n-nodes-base.if","position":[1060,420],"parameters":{"conditions":{"string":[{"value1":"={{$node[\"Webhook\"].json[\"query\"][\"hub.mode\"]}}","value2":"subscribe"}]}},"typeVersion":1},{"id":"57a9a2c5-6c68-4a46-a475-17213ed28f4d","name":"Respond to Webhook","type":"n8n-nodes-base.respondToWebhook","position":[1440,420],"parameters":{"options":{},"respondWith":"text","responseBody":"={{ $json.data }}"},"typeVersion":1}],"active":true,"pinData":{},"settings":{},"versionId":"55fe98ba-7517-4151-87d2-17223fe9df8f","connections":{"IF":{"main":[[{"node":"Set","type":"main","index":0}]]},"Set":{"main":[[{"node":"Respond to Webhook","type":"main","index":0}]]},"Webhook":{"main":[[{"node":"IF","type":"main","index":0}]]}}}