You have a private distribution group that contains both provisioned and unprovisioned iOS devices. You need to distribute a new iOS application to the distribution group using Visual Studio App Center. What should you do?

To distribute an iOS application to a private distribution group containing unprovisioned devices, you must register those devices in the Apple Developer portal. This process associates the device's UDID (Unique Device Identifier) with your developer account, allowing you to include them in provisioning profiles. Without this registration, the app cannot be signed and installed on the unprovisioned devices. Requesting Apple IDs is not sufficient for device provisioning. Creating an App Center Test subscription is for testing services, not device registration. Adding device owners to the App Center organization manages access to App Center, but doesn't provision the devices themselves.