Everyone logs in with their own mobile number and password. You decide what each role can do.
When you add someone, ScanBhai creates a login for their mobile number with a temporary password and a message you can send on WhatsApp. They choose their own password on first login.
If a phone is lost or someone leaves, reset their password or remove them, and they are signed out everywhere.
They receive a link that opens the right app store for their phone, or the login page on a computer.
Yes. They lose access immediately.
Add as many as you need; each gets only the access you choose.