I had great result with a rental carpet cleaner and homemade solution of hot water and 50/50 borax/baking soda. I don't remember the carpet cleaner container size, but I remember dissolving 1 cup of borax and 1 cup of soda in hot water and got my sand colored carpet look like new.

Says to clean it professionally

Get an Upright by Bissell or Dyson ( if you have budget). They have great range of carpet cleaning vacuums that do wonder to your carpet. A hand vacuum is not at all suffice for carpets.

That material is notoriously difficult to clean. Best to get a pro in to clean and advise them in advance what the material is. Know also that under the best of circumstances polypropylene lasts only a few years anyway.