How do users add posts

I’m creating for a customer, and am unable to allow users to add posts, or activity (unlike the demo there’s no Activity tab and I can’t see an option to add that) so nobody can add anything beyond their profile. I need to know how and where to set up so that users can register (I found on the forum to allow them to be editors which at least brings up the posts tab) but not how to have an add posts button. I noticed, on the demo, https://ultimatememberdemo.com/user/jamesblundell although I could add “posts” in Activity nothing appeared under the posts tab. Can someone explain the difference between activity and posts? I asked several times via email support but it has not been answered!

Also I have asked how to set up paid membership, we bought the full bundle and added all, and was then told I need the restrict content plugin to do this? I saw a link on the documentation to a paid plugin is it a better option than the plugins by UA and does it work? We are wanting to have free membership initially and then charge. We are very familiar with WordPress and Woocommerce, but this plugin has left me stumped as it does not seem easy to set up! Thanks

The page I need help with: [log in to see the link]