Antifreeze will never completely evaporate. It leaves behind a greasy/oily residue. The cure is to wash it out. This can be done in the car with multiple applications of clean warm water, vacuuming it up, and finally towelling it.
But some water will remain in the jute backing, and therefor in direct contact with the metal floor. It may take several days or weeks to fully evaporate, depending on it's environment.
You can have the carpet out and on the floor in about a half hour.A little longer if you have a floor console.I see you are most of the way there already.Then you can pressure wash it at a low-pressure setting, from the topside. Vacuum it. Towel it. Wait. In the meantime you can water-wash the metal floor, and let it airdry.
This would be a good time to remove and clean out the heater box as well.