Creating User Accounts for WordPress site

I am working on a website that requires me to build a “Client only section”.

Essential what this means is a separate section of the website that can only be accessed by people who I have created an account for. In this section they will need to be able to view a catalog of products and place orders for different items (they dont need to be able to pay for them through the site. Id just like it to send me an email and a confirmation email to the user when they order something).

I want to make it so I have to create the accounts, no site visitors, as I only want a few select clients to be able to access this section. The website also needs to be able to store information about each user (Name, address, phone number, email, orders etc.).

I understand building websites with HTML, CSS and PHP, and have built both wordpress and non-wordpress based websites in the past, but this is something completely new to me.

Does anyone have a plug-in (preferable an free open plugin) that would be able to do all this for me? Alternatively, anyone know of any tutorials or anything that would be able to show me how to build this?

Im still reseaching, but any help would be much appreciated.