TO pin the Evernote Web Clipper extension to the toolbar in the Microsoft Edge browser, click on the 3 dots at the top, right-hand corner of an Edge browser window, then select Extensions, then click on the Evernote Web Clipper extension, and then click on the icon that appears to the right of it, which will have a slash through it if an icon for the extension has not yet been added to the toolbar.
That will remove the slash from the icon and add an icon for Evernote, the green elephant head, to the toolbar.