Answer the people who message your Facebook Page.
There is no app to create and no credentials to copy. Connecting happens through Meta's own dialog, and everything it needs is handled for you.
Instagram comes with it
If the Page has an Instagram account linked to it, connecting the Page connects that too. They are separate accounts here, so you can run one flow on Messenger and a different one on Instagram, or deploy to only one of them. See the Instagram guide.
Whoever connects the Page has to be able to manage it at Meta. Choose every Page you want us to answer on while the dialog is open, since it is what decides which Pages we are given.
A Page answers with one flow. Deploying a second flow to the same Page replaces the first rather than running both.
Meta limits when a business may message someone, and the limits differ for the bot and for a person answering from the inbox.
For 24 hours after a customer's last message, anything can be sent freely. This is where almost all of a conversation happens, and neither you nor the bot will notice a limit.
After 24 hours the bot stops replying, and only a person may answer. When an agent replies in that window the inbox says so, because Meta allows it on the understanding that a human wrote it. Keep it a personal answer to that customer rather than marketing: sending a campaign this way is a policy violation, and it is your Page that carries the consequence.
Nothing can be sent. The inbox will say so and stop you rather than let a reply fail silently. Internal notes are unaffected, so a conversation can still be worked on and closed.
If the connection stops working
Removing our app at Meta, or Meta restricting the Page, stops messages reaching us. You will be told in the portal and by email rather than finding out from a customer.