There is no toolbar, I see nothing and there is nothing in View > Toolbars for it. The extension shows as enabled in Tools > Addons. I'm using Firefox 64.0.2, does this work for the new web extensions?
This provides a lot of very useful tools, but if it's pinned to the overflow menu, the panel it opens in is too small to use them all. There doesn't seem to be a way to resize the panel or scroll within it.