Gave this a try as instructed with recommended mods, ran into an issue that the double decker pillar prop was missing, and the highway was using regular supports.
Checked the assets report from Loading Screen Mod, and it tagged the pillar asset mod as "Asset bugs: Workshop asset uses private asset (double deck pillar.double deck pillar_Data).
It's all a bit over my head, but just giving a heads-up to all readers.

As an alternative, you may be able to use the Parallel Road Tool with a vertical height difference, and the NoPillars mod with a different pillar type, to mimic what this mod assisted with. Note that it will require direction reversal thereafter.

How do you connect other roads to it or you cant? I cant figure out how to connect them either

I'll echo a previous poster. Regular pillars in the middle appeared. Had to manually change each to the prop pillar for this road. But it looks awesome!

Can't get them to connect

so cool thx

THANKS THANKS THANKS I've been looking for this :D

Is there an exit ramp or intersection or quad/dual not double stacked conversion for these?

Hmm, sorry it's not working for you! It seems to work for others so I'm not sure what's up. If you enable the Asset Prop toolbar you could manually place the pillar props underneath the roads and see if that works for you.

Used no colliding and the result is the same. Loaded the sections in the asset editor and the pillar prop does not show up.

If you go into the asset editor and load one of the sections, do the props show up?

downloaded all assets, props and mods, tryed with floating and no colliding but I have only floating streets without any pillars every time.

@ezoger Don't use the ''Floating'' use No ''Collide" instead

That's odd. I've downloaded and tested the items from the Workshop and they work for me. It might be that you need one or both of the prop mods enabled for it to work.

The same is happening to me. I downloaded the prop and activated the prop and every asset. When placing the assets ( 'floating' is selected in NoPillars) no pillars show up.

Did you download the prop?

+Hey when I place the assets, there are only streets floating in the air but no pillars, what did I wrong?