Answer
Thank you for getting in touch. The Quiklok T10 folds (mostly) flat when not in use but doesn't attach to the keyboard. Instead, the weight of the PSR-E333 along with the rubber grips on the stand will ensure the keyboard remains in one place when playing.
If height-adjustability isn't needed, our own L-2C stand folds flat when not in use and attaches to the PSR-E333: