CriPakGUI (or CriPakTools).
PES 2021 uses a "Virtual File System." The game reads the default Konami player data from inside the encrypted .cpk files (specifically dt10_x64.cpk ). When you edit a player, the game writes the changes to the Player.bin inside your Documents folder, overriding the default data.
:The original Player.bin file is not sitting loose in a folder. Instead, it is packed inside the game's encrypted archive files. To access it, you typically need to use a tool to "unpack" the following files located in your main installation directory: dt10_Xxx_x64.cpk (where "Xxx" varies by region)
To "look into" or edit the Player.bin , you cannot simply open it with a text editor. You must follow these steps:
Here is the guide on how to find it, extract it, and where to put it if you are trying to install a mod.