To log into the FieldStack Mobile App, Simply log into your FieldStack Desktop version as you normally would and navigate to the bottom left hand corner. You should see a button like this,

Upon clicking that button, a popup with a QR code is revealed. This can be scanned by a mobile device equipped with a 2D scanner, and will log the current employee into the mobile app. 

Depending on company preferences it's also possible to log in without the QR code, simply using the same username and password you would have on the normal FieldStack desktop log in screen.