Chances are you'll check in both using the "Sign up with ClassLink" option to sign in to both ClassLink and Backpack, or by utilizing the "Register to Backpack Only" solution and coming into your district username/e mail and password. To inquire what your district e-mail and password are, please check https://elliottizohy.onesmablog.com/how-bags-can-save-you-time-stress-and-money-74325982