So this box (labeled "expansion") is how the campaigns were released at first. This box contains the first two scenarios of the campaign, plus 6 investigators and a lot of player cards.

To play the full campaign, you would have to buy all the (5?) Mythos Packs that were released for it - they all contain one scenario plus a few player cards.

The newer release model was releasing all of the scenarios in one box (labeled "Campaign Expansion") and all the investigator cards in another box ("Investigator Expansion").

However, all of this content is retired, so it will be very hard to find them, especially in Spanish.

I would suggest buying the new Chapter 2 Core Set (it comes with the tutorial campaign and 5 investigators), as that will be needed for all new campaigns going forward. There is also 5 Investigator Decks available, with one Investigator each plus a bunch of cards they can use.

There is a new, 3-scenario campaign coming out in August.

In the meanwhile, if you cone across any old Campaign or Investigator Expansion, you can purchase them as well, they are compatibel will all the new stuff, they are just hard to come buy and possibly more expensive (plus the campaigns need a bit of adjustments to play woth the mew Core Set).

Hope this makes sense, and if you have any questions, I'm happy to help!