Answer by
LeheckaG (1826)
Rain-diverters are usually installed on your down-spout(s) above the height of your-rain-water-storage-tank; or other-diversion(s) for lanscaping-irrigation, ponds, or (swimming)pools.
Carefully remove or cut-off some down-spout from the ground-up to-or-above that-height;
Push the rain-diverter OVER the remaining-down-spout above;
Measure how-much to cut-off the down-spout-section which you removed;
cut-off;
and push the down-spout OVER the rain-diverter (& INTO your-drain).
Fasten-together with screws.