On a few occasions that the Thea Toolbar is not visible after installing the plugin, there are two ways to enable it.

  1. Right-click on an empty space of SketchUp’s toolbar and select Thea for SketchUp from the pop-up or
  2. From the top drop-down menu, select Extensions > Thea Render > Show Thea for SketchUp toolbar.

You can also have a look at this quick tip video: