The sub password is set in the admin section of PowerSchool here: Start Page > School Setup > Substitute Sign In Settings (see below)
Subs will need to connect to the substitute section of PowerSchool at this link: powerschool.lakelinden.k12.mi.us/subs (REPLACE Lake Linden with your district name) and follow instructions below.
A full user guide can be viewed by clicking ps9x_substitute_portal_user_guide (1).pdf