Using Classic Outlook on Windows for personal email, calendar, and contact management
The New Teams is for some reason seen as web application and not a physical program you install.
And if you are using old outlook it will not pickup the New Teams because its not an application on the computer it self.
I have found if you upgrade to the latest outlook then when creating a meeting you have a slider that you can slide to make it a Teams Meeting again.
This works on Office 365 I have not tested on any older Outlooks.
Do bear in mind it looks like the new outlook is also Web Based and a lot of the addins don't work with it.