how do you need to add a curator for an project not a studio a project?

You can't. Projects can't have curators, only studios.

Well, projects can have curators if you're talking about the “Projects curated by ____” section of the front page, but that just means they are adding your project to the front page, they can't edit your project or anything like that.

What? Can you please clarify your question?

You cannot add curators to projects.