The installation is very easy...

1. Extract the .rar file.
2. Copy the content to the root folder -> i.e. \SteamLibrary\steamapps\common\Dying Light 2\ph\source
3. If used with different mods, not guaranteed, it will work. However, you can always change the file name as follows -> datax.pak
(x means one number up, if you already have a data3.pak in your source folder, adjust this mod (MoreSpawns) i.e to -> data4.pak or data5.pak (upwards).