Most questions are about sharing and iCloud. If none of this covers it, email me — I read everything and usually reply within a couple of days.
It helps to include your iPhone model, your iOS version, and what you saw on screen.
Adding a person creates a shared space that you both write into. You invite them once — you don't each need to invite the other. When they accept, you can both see and add orders, and every order shows who it belongs to.
There's no account to create — the app uses the iCloud account already signed in on your iPhone. Your orders are stored on the device too, so the app works offline and syncs when you're back on a connection.
Location is used for one thing: noticing which restaurant you're standing in, so the app can show the go-tos saved there. It's checked while you're using the app, never in the background, and you can decline the permission and search for a restaurant instead.
What you write in your own profile — allergies, hard no's — is shown to the people you share with, pinned at the top of your card so they see it before they order for you. You control that text and can change it at any time.
It's a convenience, not a medical safeguard. If an allergy is serious, tell the restaurant directly — don't rely on an app.
Deleting an order removes it from your devices and from anyone you shared it with. To remove everything, delete the app and then remove its data from Settings → your name → iCloud → Manage Account Storage.