PROD-I-423 RFPIO Plugin not working - Outlook - jonathan Gudger

Jonathan Gudger (jonathan@rfpio) is having issues installing the RFPIO Lookup plugin in Outlook. I've tried the following IT support (Slack + zoom screen sharing). The Outlook plugin button and also the Microsoft Store button are greyed out. We have tried the following: * DONE - Uninstall Office 365 on Windows 10 (Surfacebook, RFPIO Asset US-LAP-074). * DONE - Jonathan logs in to portal.office365.com (http://portal.office365.com/) successfully & downloads Office 365. * DONE - Reinstall Office 365. * DONE - Open Outlook & activate with jonathan@rfpious.onmicrosoft.com account. The Outlook RFPIO plugin still does not appear, same issue with the Microsoft Store button. Also tried various 'view menu options' in Outlook with the same result. Wondering if anyone has an idea that I've missed, or a tested way to get this Outlook plugin working?