Mr E's latest version's extension already displays a Mr E icon when you open LinkedIn. You don't have to pin the extension on your address bar anymore to use Mr E with LinkedIn.
Refer to the below image: Mr E extension already present when you open your LinkedIn Account.
If you are not able to view it on your window, please Reinstall the tool and Login with the same email account to access it.
You can also pin the extension the OldSchool way as follows:
Go to your linkedin page and on the top right corner of your screen, there is an icon for extensions. Once you click on that "extensions" icon, you will be able to see the option to pin the extension. When you pin the you'll be able see the Mr. E icon (the bearded guy) on the top of your screen.
Once pinned, you can now directly open the extension from the top right corner of your screen to extract the contact details of people using the Mr. E tool.