First of all! You need the truck mod(MAN TGX Euro 6 by MADster): https://forum.scssoft.com/viewtopic.php?t=185585
After you added the truck(MAN TGX Euro 6 by MADster) you can add the skins.
Tested on 1.33
Special thanks to MADster for accepting to make skins on his truck!
You have to download separated the truck skin and trailer skin.