This error might appear if you attempt to install an eSIM on a device that is locked to a specific network.
To check if your device is locked, follow these steps:
Open Settings, then go to General, and tap About.
Look for the Carrier Lock section. If it says No SIM restrictions, your device is unlocked. If not contact your carrier to unlock your device.
If you have confirmed with your current provider that your device is unlocked, please reach out to support(link).