Usually mods come in a .pak file format.
Installing those is fairly easy.
Just navigate to this folder:
Steam\steamapps\common\DRAGON BALL Z KAKAROT\AT\Content\Paks
and create a folder called ~mods inside of it.
Now just dragn n drop your modded .pak files in that folder and launch the game. You can have multiple .pak files in that folder but it always depends what the mod actually changes so some mods might be not compatible with others as both change the same files for example.