This error can occur when you try to install an eSIM on a network-locked device. To check if your device is locked, please follow these steps:
Go to Settings > General and tap About. Under Carrier Lock, a message should appear stating: No SIM restrictions. If this message does not appear, please contact your provider to unlock your device.
If you have confirmed with your current provider that your device is unlocked, please contact our support team at: support@simly.com