Hi Ollie
Polyolefin refers to polyethylene and polypropylene as ethylene and propylene are olefins.
In this case it would be PP as PE is not used for carpets.
Heatset is a clue, obviously not too hiigh a temp.
Should be easy to clean , prespray , agitate , extract temp say 45c using minimum water.
I would use my BW technique which is to spray above carpet then extarct so that water is not forced into the backing.
Cheers
Doug