To the best of my knowledge the add-in is something that is bundled with the Teams installation. So I have seen issues, where something has to be done on the Office installation, Outlook closed, Teams reloaded and Outlook launched for it to acknowledge the change but not sure of it being Teams version specific but certainly Office version specific. I can check it out though.
If you also right click your Teams icon in the system tray and do get logs, this can be helpful as part of the logs it will mention if the Add-in is loaded:
Wed Aug 05 2020 12:52:12 GMT+0100 (British Summer Time) <10572> -- info -- Current Outlook Version: 16 Wed Aug 05 2020 12:52:12 GMT+0100 (British Summer Time) <10572> -- info -- Outlook meeting addin registered success Wed Aug 05 2020 12:52:12 GMT+0100 (British Summer Time) <10572> -- event -- name: meeting_addin_registration_success, contextForAddin: teamsUpgradePolicyV2Synced, ppChannel: Insiders::FRDC, distSrc: PROPLUS_ProjectProRetail,O365ProPlusRetail,VisioProRetail, ppInstallMode: INSTALL, autoStartPolicy: undefined, vdiMode: 0, eventpdclevel: 1,