Believe that they are open-sourcing the client but cannot confirm. It is built on open source tools, like Identity Overlay Network (ION), Bitcoin and Lightning, though.

The creator account isn’t necessary unless you want to create a community (these are generally for musicians, artists, themes etc). It’s free for general users.

It also has native lightning wallets built in.

I think of it as being more of a tool for people to get paid by their followers and for interest groups / communities.

Definitely worth checking out.