This software, Ghost, is built around a subscription model.
What that means is that the application will email new posts to you once you provide email details. If you do not wish to subscribe, the public content is available by returning to the site, but you will not be notified of new posts.
It also provides a way of providing access to material that is not published to a public audience. It may be that articles that might be blocked by a pay wall and such could be made available through this method. It remains to be seen whether this would have any utility.
The application also provides functionality for accepting a payment for subscription. Initially this is not enabled or necessary. The only reason for it to become necessary would be if cost of publication and site maintenance became onerous and or the extension of source material subscriptions.
It should be made clear that all personal information gathered through the application is retained on site, it is not transmitted onto any cloud storage or other entity. It will not be used for any purpose other than the stated purpose of distributing content from this site.