How high must I install a new Junction Box for the Ring Floodlight Camera?

I plan on installing a Ring Floodlight Camera. But, since there is not a current floodlight where I want to install the Ring Floodlight Camera, a new junction box must be 1st installed. QUESTION: In order to have the motion detector part 9' off the ground as recommended by Ring, how high must I install the junction box? I need to know what the distance is from the **"top"** of the junction box to the **"bottom"** of the motion detector part.