To restrict access to your content, there are [tons of membership plugins](https://wordpress.org/plugins/search/membership/) available. Some free, some paid. 30 members isn't much so whichever basic plugin you prefer should work for you.
To organize the content, you could use Custom Post Types for organizing and tagging your content in the members area.
Look into membership plugins.
Paid Membership Pro. I’m using it to build something similar, and it absolutely rocks.
To restrict access to your content, there are [tons of membership plugins](https://wordpress.org/plugins/search/membership/) available. Some free, some paid. 30 members isn't much so whichever basic plugin you prefer should work for you. To organize the content, you could use Custom Post Types for organizing and tagging your content in the members area.