1- Create a Workpress app https://developer.wordpress.com

2- Add redirect the generic redirect URL to your Wordpress app
ex https://mybubbleapp.bubbleapps.io/api/1.1/oauth_redirect
or https://mywebsite.com/api/1.1/oauth_redirect

3- Add the app ID (Client ID) and app secret (Client Secret) to your plugin

4- To authenticate a user add it as a social network login/signup action

5- Show your blog posts in repeating group using a website id