raw materials

[grand spade]

can i substitute the raw materials with the cargo harbor?

[mint canopy]

if you are asking whether you can import raw materials (raw crops, raw ore, etc) by ship, the answer is yes. But only to a point.

There's a limit to how much traffic each outside connection can allow

if you have ships AND railways AND highways, and multiple of each, you may be able to import quite a lot

but even a single one should be able to import everything you need for all the unique factories