How to configure system shares?

I'm completely new to owncloud and are having difficulty understanding how to configure system wide shares. I see lots of detail on how to create personal shares, but what if I would like to provide a system wide share with some users that have read only and some users with full access? What is the best way hp to achieve this? Is it to set up a dummy user? Or is there a better way? Any helpful information please

Put all users into one group and then you can share folders system wide with this group.

Yes, that's often used in organizations when you don't want that a folder belongs to a specific user.

Documentation for such "persistent shares" is avalailable at https://doc.owncloud.org/server/latest/admin_manual/configuration_files/file_sharing_configuration.html#creating-persistent-file-shares