Tip: open an existing conversation and use “Copy Messenger ID”. Meta only allows outbound messages to people who have messaged the page, subject to the 24h/7d messaging windows.
⚠️ Missing Permission: Your Facebook token needs pages_messaging permission to read/send Messenger conversations.
Click the green "🔑 Get New Token" button above, authorize, then copy the new token from the URL bar and paste it in the token field.