The Scroll Progress Bar Element can be implemented in several different ways. With the Progress Bar Position option, it can be Fixed to the Top, or the Bottom of the Viewport, or it can be set to Content Flow, which essentially means you can place it anywere in the content.
So the first thing to decide is where you want it positioned. With both Fixed To Top, and Fixed To Bottom positions, the Scroll Progress Bar extends the full width of the Viewport, and regardless of where you place the Element in your page content, on the front end, it is postitioned at the very top or the very bottom of the Viewport. If you have a Sticky Header, it remains above the Sticky Header when active.
When using the Content Flow Position, the Scroll Progress bar remains in the flow of content, wherever you have placed it, but is then also limited to the container width you set. There is a Z Index option, that allows you to ensure the bar is seen above other content, and several design options to control the colors and size of the bar, and even border options.