How to Create a Limited Access / Invitation-Only Login Page Like This?

Hi,

I found this login page setup on a FreeFlarum forum:

It blocks all content unless you're logged in.
How can I achieve the same on my own Flarum installation?

Is this done with an extension or is it custom-made?

Thanks!

This is done by the Private Forum Facade extension

Capybara thank you 🙂