Importing a classroom from Microsoft Teams is very simple, and you don't even need to use a Sign in with Microsoft teacher account to use it. To get started, simply go to your Classes tab and click the "Import from Microsoft" button

You will be prompted to choose a Microsoft Teams account, then a team from that account.

Simply click "Import Roster" to make make a new classroom and import your students.

If your Microsoft Teams Domain is part of a network, you may be prompted with one of these two screens instead

Or this one:

In this case, you will need to get admin approval before Microsoft Teams will allow you to use Boom Cards. Either sign in with an admin account, send an email to your admin or IT department, or enter a request for your admin into the text box and click "request approval" to send them a message through Microsoft Teams. If you use the "request approval" feature, they should receive a request such as this one:

You can also ask your IT person to go to the Boom Learning help page and click on the Microsoft button there.

This will help them to set up the configurations in a less confusing way than going to the Microsoft Portal.

Once they have accepted it, you can import Microsoft Teams classes like normal.