I really got nothing from there. Once you are there, just click on the rhythmverse logo. You’ll be directed to the home page. You won’t be able upload songs but you’ll at least be logged in. I’ll let you know if I figure out the whole invite token.
You are about to leave Rhythm Gaming World and access the external songs DB. While no song or file sold for commercially available videogames is hosted there and only fan generated content is allowed, Rhythm Gaming World has no direct control over the database and no files are hosted here. Alright, we had to made you aware of this, now you can visit the database!