The extra "Separator" element is needed more for visual separation of elements. To add the "Separator" element to the form, you need to click on the selected item or drag it to the right, then you will see the added element on the right:
After you have added the "Separator" element, click on the "Edit" icon and a pop-up window for editing this element will open in front of you:
In the element editing mode, the element width settings and css settings are available:
To view an already configured form, click on the "Prewiew" icon and the form will open in a new tab in your browser:
We remind you that the value and description of other fields, you can see here "The main parameters of the elements".