I'm somewhat familiar with the acoustics of opera houses and concert halls, but I couldn't even venture a guess here, as it seems to be a translation from some third language. (It should apparently say there is carpet on the floor and fabric on the walls, though if that's true, it may affect the acoustic, as most halls need some hard surfaces to reflect sound.)

Your guess about some kind of Anlage could be right, or who knows, there could be actual green plants in planters near the ceiling. Or there could be some kind of typo or misunderstanding involved.

If I were you I would ask, or maybe ask for a picture.