How to create Facebook Application and authorize with Facebook

I was following these steps in the document above, but now I get a message that says

This content isn't available right now When this happens, it's usually because the owner only shared it with a small group of people, changed who can see it or it's been deleted.

I was trying to generate the Facebook App ID and Security ID for a plugin. Now when I click on the Facebook icon on the website the Facebook page does not come up unless you are logged into Facebook.

The website:

Help! I don't know how to fix this.

Asked about a month ago