What is the ruling on receiving or handing over money or documents that result in money with the left hand, and does this action make the money unlawful?

What you mentioned does not affect the lawfulness of the money, as long as it was received through a transaction permissible in Islamic law. It is recommended to take and give with the right hand, based on the general narration of Aisha, may Allah be pleased with her, who said: "The Messenger of Allah loved to start with the right in all his affairs," and his (peace be upon him) saying: "Let one of you eat with his right hand, drink with his right hand, take with his right hand, and give with his right hand; for Satan eats with his left, drinks with his left, gives with his left, and takes with his left." Taking and giving with the left hand is an imitation of Satan and contrary to chivalry and good manners, unless the right hand is occupied and what is in it cannot be transferred.