Is this your sump?
Sump
Volume Capacity - 57 Gallons
Dimensions - 38.6"L x 18.8"W x 18.3"H
Filtration - 3x Filter Media Cups with High Performance Fiber Ball Media
Protein Skimmer Chamber - 16.3"L x 11.4"W
Protein Skimmer Cover Plate Opening - 9" Diameter
Refugium Chamber - 16.3"L x 11.9"W
Return Pump Chamber - 15.3"L x 6.5"W
Plumbing -
3x 1" PVC Bulkheads
1x 3/4" PVC Bulkhead with Hose Barb Fitting
1x Reversible 1/4" to 1/2" ATO Reurn Hose Barb

Maybe a thin piece of foam over the cup section of your sump might be enough to get it to be quiet.
Option 2 is to add foam pads above the fiber ball stuff they gave you.
Option 3 is to raise the water level height in that section.
Option 4 is to replace the fiber ball media they got in there with just foam pads or pot scrubbers.
On my diy sump the water exits about 1" below the water line in the "silent chamber" and flows over on to the polyfil on top of the foam blocks. The distance between my mechanical media and the spill over is pretty short, like about 1".