Since this was harder than you expect it to find on the main announcement page...the page you want to go to in order to actually access teams is here: https://teams.microsoft.com/

And the app downloads page is here: https://teams.microsoft.com/downloads

I'm getting an error on my end though after following their activation steps so I need to figure out why it's doing that. (Shows me "errorCode=AdminUserLicenseNotPresent" so maybe there's an extra step I have to complete that wasn't mentioned)