You can use the meta API , and retell API
Meta , will send you a webhook with the user message -> you will take this message and sent it to chat compilation API will generate you a message from the AI agent, will take this message and send it back to meta channel
Meta webhook sends message -> retell generate a response -> send the message back to meta channel
their some logic in the middle like keeping the session between each users and handle the tools calls , but its doable.