I don’t know what the problem is, but the elevator is not working. It just consumes electricity and produces nothing. And if this is possible, how to get into the cave? There are no conflicting mods.

In the cave, you need to make conveyor belts go toward the elevator on the left/right side, in the middle. You then need to make the belts go away from the elevator on the surface (same position, left or right of elevator aligned in the center) and items will be transported to the surface. The elevator needs power.

To get into the cave, you must "enter" the bottom of the elevator by walking to it and enter the top once in the cave to exit to the surface.
There are screenshot of the conveyor belt position on the mod's page. But I never explained how to enter the elevator, I will add it to the mod's description.

Thanks for the answer. The mod is interesting, but little was clear from the description.

Too much slag? No place to store it

Slag is used later to produce more ores. Before that, or if you can't refine all of the slag, you can turn it into stone, then into landfill if you can't use all of this stone.

thank you ^-^!