Ransom money in the Old Testament was collected when a census was taken. It was for the service of the tabernacle of the congregation. The deeper meaning is that it cost something for our salvation. God paid a price to ransom us from our sins. He gave His very own Son!
Matthew 20:28 Even as the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many.
The debt has been paid. The Creator has paid the price to bring us back to Himself!