First, create an account in the Aurinko portal

When asked about the type of app you want to create chose 'Teams/Slack app':

Next, check API/features that should be activated for your new app. Besides 'Chat' and 'User sessions' your addin may need to access CRM APIs.

Now, go to the 'Check out your first Teams app!' todo item on your Aurinko app's dashboard page and download your app package. 

You're ready to activate your MS Teams app!

Installing MS Teams app.

Once you've installed the app, opened its tab, and confirmed your id, you'll see a new user record in Aurinko:

Now you frontend code can call Aurinko API on behalf of this user. Read this article for more details.