Does anyone know how to add a phone on Find My for my husband?

My husband travels a lot for work and I’d like to be able to see his location for peace of mind. I’ve tried going into the Find My app but I only see my own devices. Is there a way to add someone else’s phone, or does he need to share his location from his end? Thanks!

He needs to share his location from his device. You can’t add his phone without his permission.