Connecting Facebook pages & Rubo.io
Extension are based on rubo.io service, so you have to have an account there.
First of all please go to https://app.rubo.io/ and login to your account.
Connecting Facebook page
Please click on the button "+ Connect page"
Click on "Connect new Facebook Account"
That's all. Now you will see this page in Magento configuration and will be able to send the message from this page.