A Max Drive lets you transfer option files and other memory card files between your pc hard drive and your memory card. There is a max drive for ps2 and one for xbox.
It has nothing to do with patching your game.
You download an option file where people have updated all the data using the ingame edit mode and transfer it to your own memory card to play your game updated. Examples of these updates can be seen in the first post of
this thread.
and shown below too:
There have been 2 updates for this file since the release and the latest one is now the pesfan V3 file which can be found in the File Downloads section.
A max drive can be used to transfer any memory card file for any ps2 game. So you could download save files for other games too. Download PES4 option files saves you many weeks worth of editing the game by yourself and is usually done by people who have a good knowledge of specific teams or leagues working together. Having a max drive will save you from having to buy more memory cards too.