An awning should be waterproof, but some new ones do need to get wet so the stitching swells into the needle holes before they keep the rain out. Is yours a brand new awning?
Pitch so any rain will run away from, rather than towards, your caravan/awning is the easiest bet, but not always possible to do of course.
Awning carpets are 100z% waterproof but that doesnt mean they cannot get wet. Many sites will not permit groundsheets (thick plastic sheets) because although they stop water seeping up through them they also kill the grass they are on top of.
Basically a wet floor in an awning is something you have to learn to live with. Unless of course you are on a seasonal pitch, then you could lay down some pallets to lift your awning floor off te ground and away from any water.