Try best to avoid storing anything in shared folder of Qlik Sense. The deployment of Qlik Sense is different from QlikView.
You directly create apps/extractors from your work area(it eventually gets stored in the shared folder). The apps are then published to streams(you can decide who access what stream via security rules)
I've worked with Qlik sense access rights and folder structures at multiple companies. The need for securing applications and data differ a lot. I would recommend you to ask the business or system owner about their data.
In QlikView (and Qlik Sense) I've worked with the Qlik Deployment Framework for handling these folder organizing questions, I really recommend you to take a look at the QDF documentation even if you are not planning to implement the framework. There QDF has it own forum here at Qlik Community.