Salesforce for Excel Connector Office 2016
Thanks so much for your help.
Specifically the following steps should make it show up in the add-ins tab:
5. Run Excel. Click on the green "File" tab, then "Options" (second from the bottom).
6. Click on "Add-Ins" (second from the bottom again), then at the bottom of the page, Manage "Excel
Add-ins" click "Go" button.
7. Click the "Browse"
button on the Popup form and locate the "sforce_connect.xla" file you saved.