I installed the plugin, but I don't see it in the Dashboard

When you finish installation and activate the plugin, the Cost Calculator will appear as Visual Composer element. When you navigate to the page editor you will see the Cost Calculator suggested on element list.

If you are not using the Visual Composer as a page builder, than the best option is to install our demo pages in order to see how all Cost Calculator are set. Please refer to the following article: Importing Demo.