In order to configure the auto-publication of your blog posts on Facebook in Magento 2 Blog navigate to Stores > Configuration > Magefan Extensions > Blog and find the Publish Posts On Facebook section. Note that this option is available for Blog Plus and Blog Extra users only.

1. Enable the Auto Publish on Facebook option to be able to configure it.

2. Set the Facebook App ID and Facebook App Secret. You need to get them from your Facebook API. If you don't have one, please create a new Facebook APP. Note that the application needs to be in the LIVE mode and  "manage_pages" and "publish_page"  permissions should be enabled.

3. Enter the Facebook Page ID (?). This is the page your blog posts will be automatically published on. Use this link to learn how to create a Facebook page in case you don't have one.

4. Select the Blog Categories For Auto Publishing to state the categories you want blog posts to be automatically published from.

Publish posts on Facebook configuration

Once you've filled all the information and pressed the Save Config there will appear the following notification. You will need to generate a new Facebook Access Token by following the link.

Publish Posts on Facebook Configuration

You will be taken to the Facebook page to generate the Facebook Access Token.

1. Confirm it is you who's trying to get the access.

 Fcaebook access token

2. Choose the Pages you want to be used by the APP for publishing your blog posts on Facebook.

Facebook access token pages

3. Enable all the Options APP request.

Facebook developer access

After you have finished there will appear the confirmation about your account being successfully linked to the Facebook APP.

Facebook access token

Now your new articles will be automatically published on Facebook.

Troubleshooting

In case you want to disable the auto-publication to Facebook of some particular post go to Content > Post and chose the post you want to disable from sharing. Then, scroll down to the bottom of the page, find the Publish On Facebook section and disable the automatic publication of this page on Facebook.

Blog post configuration