FIFA 13 is an older game. Windows 10/11 memory management often confuses old Unarc.dll files.
For 90% of users, running as admin fixes it. If not, the 4GB patch will. Leave a comment if you're still stuck." how to fix unarc dll returned an error code 6 fifa 13 link
Error code 6 specifically can sometimes mean "Read Error." This happens if your RAM is faulty or your hard drive is full. FIFA 13 is an older game