What do my crew need on their phones?

Just a phone with a web browser. Invite them from People, Crew; they open the invitation email, sign up and see their own jobs. Adding the app to the phone's Home Screen makes it open like any other app, and on an iPhone it keeps their saved jobs and lets it send job alerts. The app shows them how the first time they open it.

On the phone they clock on and off, add parts, photos and notes, fill in forms, and finish the job with the customer's signature.

See Put the app on your phone and Your jobs.