Effectively, there is no documentation on how to do the login, however it works as follows:
curl -X POST http://127.0.0.1:7001/MagicInfo/auth -H 'content-type: application/json' -d '{ "username" : "admin", "password" : "admin2016"}'
a POST request to the authentication path, sent json parameters, (username / password)
Regards!!