That is not a site nor a file that Digi would support. You are most likely going to need to contact the creator or check on a forum on that site for the info you are looking for.
While I actually gave up on it and am now rigging my own code for communicating with the xbee on that device, I want to point out that the library is marked as official at http://examples.digi.com/quick-reference/, and that it’s hosted in digi’s github account.