OneNote not connected to Outlook

I need a user at work to have OneNote connected to her Outlook.
     She had both "OneNote 2016 and the newer "OneNote." In her Outlook, when she clicked the OneNote button, it opened the older OneNote (OneNote 2016). She wanted Outlook to open the newer one (OneNote) but I could not get her Outlook to do that. So I had to delete OneNote 2016 (which entailed deleting some .exe file, because it wasn't listed in her "Programs and Features" and thus I could not delete it from there). But then that caused her Outlook not to be able to use any version of OneNote. So I had to delete her Microsoft Office. But then I couldn't re-install Office because she also had Visio and Project installed. So I had to uninstall both those products. Then I was able to re-install her Office, and then had to reinstall Project and Visio.
     Now the OneNote button is not visible anywhere in her Outlook.
     In her Outlook I went to "Options \ Add-ins." OneNote is not listed as an active application nor as an inactive one (it's not listed at all). When I set the drop-down box to "COM Add-ins" and click "Go," OneNote is not listed there either.
     She currently has Office 2016, 64-bit.