Back-end Script
On your server, you should create an end point (called by your front-end) which will create a session for a user. To create that user session you will need to call the Mindset SDK Users API (see the SDK Users API documentation for more details). You must provide anexternalId or a userEmail parameter so that the Mindset system can identify the user.
The SDK Users API returns a {authToken} which has to be used in the Front-end script (a getAuthToken() method passed to the mindset.init()).
See the doc for more details about Authentication flow.