Getting message "You're not on Teams yet..." when I try to sign in with the web and windows app

I signed into Teams with my personal email address and get the message "You're not on Teams yet, but you can set it up for your organization."  However I am already signed up, I tried this with both the web and windows Teams app and get the same message.  I need to use the Teams free windows app, how can I get past this?

Edit: I also tried going to the main product page for Microsoft Teams, clicked the "Sign up for free" link and provided my personal email address (linked to a Microsoft account) at the login page, then before I could enter my password I got the error message "You can't sign in here with a personal account. Use your work or school account instead".  But Teams free can only work with a personal account???