Navigate to Channels → Add Inbox → WhatsApp. All you need is the phone number you already use for WhatsApp Business.
Follow the setup wizard: Qontaktly provisions a dedicated WhatsApp Business connection for your property and shows a QR code. Scan it with the phone you want to use for WhatsApp Business.
Once scanned, every message sent to that number lands in your Qontaktly inbox. Replies go back automatically.