Most of the Creation Club content is created internally, some with external partners who have worked on our games, and some by external Creators.
Also, we won’t allow any existing mods to be retrofitted into Creation Club, it must all be original content. Mods will remain a free and open system where anyone can create and share what they’d like. But here's the answer to the question: 'Is Creation Club paid mods?' which is at least an admirably straightforward question:
So yes, we are dealing with a real money storefront here, something the announcement video didn't make entirely clear.