In Impero back:drop, each student's profile contains their unique login details. These login details can be used on as many devices as they need.
To set a student's login details, on a student's profile, choose "Change Login" under Settings.
Students have auto-generated login details, which you can override by changing them in the "Username" and "Password" boxes, then pressing "Save Changes".
Choosing "Print Details" will allow you to print a PDF of the individual student's login details.