But here it seems you have autopromote=true turned on for your room. So, any user who comes in as guest is getting autopromoted to presenter role and is getting all controls. You can change this property either through dev console by logging into your room or through programmatically in your application by changing RoomSettings.
LoginDialog.mxml actually has code that sets autopromote=true and so you are seeing full control when you are going in as guest since you are getting promoted to presenter role.
As a guest, you are allowed to download the file. You can do this either by double clicking or by selecting the file and clicking on 'Save Selected File'. But you can upload or delete a file only if you have a host or presenter role ( i.e. userole 50 or above)
FileShare Pod is added in the example LoginDialog.