How to get the turrets to work?

You'll need ammo to get the turrets to work. We explain how to do this in detail in this answer:

https://www.appgamer.com/sandship-crafting-factory/how-to-obtain-100-yellow-everstones

But basically you need to set up as follows:

Synthesizer > Grabber > Mechanical Assember (with recipe set to Ammuniton) > Grabber > Turrets

In the screenshot above we have placed extruders to help protect the turrets.