I've found that this didn't work! Anon users only have view not read access and no where to change it.

So if I tweeted a direct link to a file, an anon user would be directed to a logon box. If they went through Sharepoint and found the file manually it opened.

Also if they tried to browse directories the same thing happened.

This addon: https://xenoxgaravito.sharepoint.com...Post.aspx?ID=8 works wonders.

You have to add it as a web part on a page. I've just hidden it.

The settings I've found that let anon users open files direct from URLs and browse directories are:

ViewListItems, OpenItems, ViewFormPages, Open, ViewPages, BrowseDirectories, AnonymousSearchAccessWebLists

I use the public Sharepoint as a parents portal. We upload flyers, newsletters, letters etc there. Makes admin much easier than having to upload and link in Joomla.