Do you have the "Euro Truck Simulator 2" folder in the "Documents" folder of your computer?

it seems very strange to me: when you install ETS2, the "Euro Truck Simulator 2" folder is automatically created in the "Documents" folder of your computer (not ets2 steam )..
Inside the "Euro Truck Simulator 2" folder is the "Mod" folder.

as @Citelis730 told you, the Ets2 mod folder is usually located in C: \ Users \ ...... \ Documents \ Euro Truck Simulator 2 \ mod)....
see step 9 of the tutorial

ATTENTION!
ProMods 2.46 (Single or Multiplayer) is not yet compatible with game version 1.38. Please downgrade your game to 1.37

vous pouvez vérifier ici, selon la version que vous avez ...
https://www.promods.net/compat.php

Hey guys .... ... we must try to respect the work that the developers do: they are not paid and spend most of their free time creating maps (for free!) for our enjoyment! and it's not an easy job !! So let's avoid asking constantly, annoying them with useless and repetitive requests: the posts are a...

in fact .... the beginning is not the best

check in this page...
https://www.promods.net/compat.php

follow this order...
https://www.promods.net/viewtopic.php?f=42&t=29618

ProMods 2.46 no es compatible con la versión 1.38 del juego.
Están trabajando en una actualización.

si quieres usar Promods, baja tu juego a 1.37 .....
https://i.ibb.co/prdtNdR/Screenshot-82.png