When you are sharing a document folder with users, or probably you are the user that a document folder is being shared with, the document folder can only be read-only or read and write only by the user. Hence, the extent or level to which a user has access to a shared document folder is either read-only or read and write.
A user would need the permission of the admin to further access the folder, probably to delete it or whatever. Actually, when you first create a folder, it has the same permission that the parent folder has.
So, you will have to set the permission to the level you actually want. The levels of permission range from full control to modify, read, and execute, list folder contents, read, or write. These levels are arranged in order of higher-level access to the least level. So, this should guide you when setting your permission to a document folder.