Entirely new site?

I'm a little confused looking at this but it may be I simply don't understand the concept.

Question: This theme seems like it would be great for the help section of a website. But it seems like it would require it's own blog backend. Am I understanding this correctly? That would seem counter to seo and logic - to have a completely separate site for help. But perhaps I'm wrong and it's common to break out site help and forums onto a completely different site? (It would be cool to use one forum and helpdesk to support multiple sites - if that wasn't too confusing for the user).

Any insight on how this is meant to be used would really be appreciated. And I apologize in advance if the answer should be crystal clear. It's just that as a new user I go to get the theme and - oh no - I've got 3 choices!