The only supported version will be the latest one, so make sure you have it if you want to receive some assistance in case of issues.
You can download the Plugin from the Official Sponge Ore Page
The only place to report a bug or an issue is the Issue Tracker of this repository.
You can also use topics on the Sponge Forum or the Plugin Discuss Page but note that the Issue Tracker should be the preferred way, simply because anyone can read about the current issues of the plugin, and so if others have the same issues they can know when they got fixed.
DO NOT SEND EMAILS. Both for the reason described above and because they often go into the spam folder, and so they can get lost or I can read them even months after you send it. So please, if possible, again, use the Issue Tracker (is literally there for this reason)