https://github.com/ItsDeidara/MegaNTR/blob/master/Plugins/plugin/Tales of the Abyss_USA/0004000000061300.plg
Open that page and click the download button, see if that works. Be sure the plugin is inside a folder named with that title id.
Oh, it has to be in a folder? I thought it just went into the plugins folder itself, not in another folder within it. Maybe that's the problem... I'll check in a few minutes and report back. The numbers in the plg file are the title ID right?