When you unpack your mods, make sure you take your time and follow the directions provided in the tutorial video.
Sometimes you'll find that mods like @CUP_Terrains_Core like to make subfolders when unzipped etc, make sure that all of your @Modname folders contain an "Addons" folder. If they contain another @Modname folder, you need to remove the second layer.
For example, this is incorrect:
Steamapps\Common\Arma3\@CUP_Terrains_Core\@CUP_Terrains_Core\Addons
It should be:
Steamapps\Common\Arma3\@CUP_Terrains_Core\Addons
Remember that over 100 people have this modpack installed, so the unfortunate truth is that any errors you come across are because things aren't installed properly, and not because the modpack is "broken".
Follow the instructions slowly and carefully and you should be fine.
IF you still have issues after that, make sure you collect information such as the specific error being received, what your mod load order is, at what stage the errors pop up etc.
We're always happy to help and the more information you can provide, the quicker you'll get a possible solution.
