How to Auto Publish to Buffer from Wordpress:

In order to post updates through the Buffer API you'll need first to create a Buffer App here:
https://buffer.com/developers/apps/create

For 'Callback URL' you can input http://example.com

Once you've created your Buffer App copy your 'Access Token'.

This is it, with 'Access Token',
You can add your account in the Social Accounts section of MicroblogPoster.