How does maryland v. mcculloch relate to federalism?

Well.. for one:
They helped balance the Federalism..

Chief Justice Marshall's decision in McCulloch v. Maryland says an action or law of a state cannot impede the valid constitutional exercises of power by the Federal government. By demarcating a clear line between federal and state power, it allowed for a more cooperative relationship between states and the federal government
Hope this helped :)

Good luck : )