The load sensor must be fixed central under the car between car frame and car floor. The load sensor must always touch the car floor. To ensure that, the load sensor must be clamped between car frame and car floor.
If there are buffers between car frame and car, the load sensor must have a buffer too. If the car is fixed directly to the car frame (no buffers between car and car frame) you have to use a screw instead of the buffer on the load sensor. To change the height of the load sensor please use some spacers (sheet metals or something similar).
If the weight in the car increases, the distance will decrease between car frame and the car floor. Because of that increases the pressure on the load sensor and that will be evaluated from the load weighing unit.