Cubik Studio

I can rotate the 3D preview, scrolling works but dragging with mouse buttons doesn't. Need help

In Preview edit-mode you have to modify how the model is displayed by editing the values in the Helper (displayed on left of the screen by default).

What is your issue exactly?

If by "3D preview" you mean the "Main" view (in 3D), you can only move elements by clicking on the axis or handles of selected elements.