Unable to generate facebook link preview

Hi, I can’t seem to get the facebook link preview to work for aticles. I’ve tried using the debugger and it says the following for articles.
-“The ‘og:type’ property is required, but not present.”
– “The ‘og:url’ property should be explicitly provided, even if a value can be inferred from other tags.”
– “The ‘og:image’ property should be explicitly provided, even if a value can be inferred from other tags.”

When i try with a page, the link preview says “Unauthorized Access” and gives a 403 response code and says
-Check that the webserver is running, and that there are no firewalls blocking Facebook’s crawlers.
-The ‘og:image’ property should be explicitly provided, even if a value can be inferred from other tags.

The page I need help with: [log in to see the link]