Just about any 6S capable 60-100A ESC will work. Not the one you linked though, because it only supports up to 4S, instead of 6S. But I would also suggest you reconsider.
500KV x 6S x ~4V per cell = 12000 RPM. Whatever you intend to use as gears to get that down to a walking speed, Im not sure I would want my little girl close to that. Or for that matter, to a 240WH lipo battery.
If you want something to go slow, yet have enough torque to move a (small) human, you may need a brushed motor. And they tend not to be cheap...