Users make a post without backend access

I am running a community based website and still in the development stages. I’m going to get a few users to help test everything soon but before i can open that up I need to get something.
What needs to be done:

A form that users can fill out on a page that sends it to a post. Before that post is made it has to be approved by an administrator first. The person wanting to post also has to be logged in before they can see the form or else it redirects them to a register page. Is there anything out there that can do that? Or do i have to pay a dev to write up something specifically for my website. Thanks