Problem when copying Steam game to new PC

[smythey]

So i just wanted to copy my backup copy of team fortress 2 to my new pc's steam folder and i get this error saying that i need 5.86eb to copy the game.

Screenshot:
https://postimg.org/image/vvr5b5mez/

 

[Colif]

lol. that would be one big drive. it wants 5.86 exabytes. considering we don't have drives big enough for a petabyte yet and an exabyte is 1000 petabytes, that seems excessive

bit
byte
kilobyte
megabyte
gigabyte
terabyte
petabyte
exabyte

they all go up in groups of 1000 so i am probably wrong here but 1 exabyte = 1 billion gigabytes.
5.86 exabytes = 6292127088.64 gigabytes.

Either way, that is not even close. Where is the backup copy located?