How do you build a cargo ship in Pride and Peddlers scenario?

[Otto Abnormalverbraucher]

I'm currently hard stuck in this scenario with the quest "Sinking the Admiral", because I need to sell a Cargo Ship or Atotolin or Great Steam Clipper to Isabel. However, I can't find out how to build a Cargo Ship, because it requires a resource I've never seen before. I don't know what this icon shows (my guess is an engine?) and I can't hover over it as it's only shown in a tooltip when I hover over the ship button (the icon on the bottom left of the tooltip with the "0/35"). I've checked all my build options (I have 500+ Artistas) but can't see anything yet to unlock with more Artistas besides Jalea, which it obviously isn't. I've also checked all the vendors whether they'd sell these things, but none of them do. I also need the same thing for an Atotolin, and I can't even find any way to build a Great Steam Clipper. Do I *have to* sell the one Great Steam Clipper I got from the start of the scenario? If so, why even give me the other "options"...?

https://steamcommunity.com/sharedfiles/filedetails/?id=3226521311

[Sir Rounded]

The game won't show you anything that unlocks past the next milestone. For example, since you have 500 artistas, you can see what will be unlocked at 900 artistas. Once you have 900 artistas, you will be able to see what unlocks when you have 1800 artistas, etc.

It looks like what you need to unlock for the cargo ship is the Motor Assembly Plant. Those are part of the production chain for Fans, so they should unlock at 4000 artistas.