Does every staff member need an email address?
Yes. The email is how they sign in, so staff who use NestliCare can't be added without one. Any address they can actually read works, including a new free one.
Yes. A staff member's email is their sign-in identity, so there is no way to add a staff member who signs in without one. In the iPhone and Android apps, the Add staff button stays greyed out until first name, last name, and a valid-looking email are filled in. On the web, Add Staff Member stays clickable and the form tells you what's missing when you save.
A phone number in the email field does not count, and neither does leaving it blank.
If you are hiring a helper who does not have an email address (a relative, a neighbor), any address they can actually read works: a free Gmail account made for the purpose is fine. It needs to be theirs, because their invitation and password resets go there, and it must not be an address already used by another staff member here.
If their email already has a NestliCare account, that's fine too. If they're a parent at your daycare, the staff role links to their existing login straight away. If their account is at another daycare, you'll be offered Send an invitation instead; accepting from their existing login adds your daycare to it.
Related: Invite your team, Why is Add staff greyed out in the app?, Can a staff member also be a parent?.