How do I change the background of Microsoft Teams when I only have a personal free account?

Hello,

I have an remote interview scheduled with a company that uses Microsoft Teams as its video conferencing app.

I have signed up for a free personal Microsoft Teams account, however, thru this, I can't even log in. I can login thru the the web app, however, there is no place there where I can change my background. My office is in my 'unfinished' garage. I am not going to be on a video conference interview with that in my background.

EVERY OTHER VIDEO CONFERENCING APP ALLOWS YOU TO DO THIS WITH THEIR FREE VERSION!!!!

I seriously will tell them "I will not use Microsoft Teams for the interview" for the reason stated above.

If I am missing something here, can you direct me how to do it. This is not an acceptable answer:
"Wait until the other party schedules the meeting and once you join, you can change your background"

Thank you,

Steve Braich