If you are trying to assemble the FitGirl Repack from multiple parts like part02.rar , here is the step-by-step guide to putting the text/files together and ensuring a successful installation: 1. How to "Put Together" the Files

: Always right-click the ACU.exe and select Run as Administrator to ensure the game has permission to save progress.

Managing your saved games in Assassin's Creed Unity | Ubisoft Help