Hi Nemix,
Polyester is a fabric (not a membrane) and would be more breathable than a polyurethane membrane (which is bonded to a fabric) but it wouldn’t be waterproof.
The product you linked is designed to be used as a dust mite and allergy encasement and there is more about allergy encasements in post #2 here.
It shouldn’t cause an issue with breathability under your mattress.
Phoenix