LVL01.KWN is a patch file which you need to replace in exact directory:

Steam version:

\Steam\steamapps\common\Asterix & Obelix XXL 1\XXL1Resources\K\LVL001

Gog / cracked version:

\Asterix & Obelix XXL Romastered\XXL1Resources\K\LVL001

Patch is needed if you want to make full runs from the save slot "GAME 1" - remember that after opening the save, you need to go back to the 1st point on the map and from here start your runs.

Patch works also when you enter the game by clicking "new game" and selecting difficulty (you will spawn as Asterix at the same place as after intro).