That is beautiful site you’ve created! Great job! 
As for your question…
With WordPress I can have unlimited number of users register and login and they can be admins, content creators, anything I want them to be.
What you are describing is a web app. At this time you cannot create a fully functioning web app within Webflow. However, you still can design/build the front-end of your web app within Webflow.
After you have done that, you can easily export your site’s static HTML, CSS, JS and images.
For more information on this, please refer to this article:
http://help.webflow.com/features/exporting
Alternatively, a community member is working on this:
Hope this helps 