Yes, your phone must be unlocked in order for you to activate your eir eSIM.

To check if your phone is unlocked:

• For iPhone: Settings > General > About > Carrier Lock: If it says ‘No SIM restrictions’ your phone is unlocked.
• For Android: Settings > Connections > Mobile Networs > Network Operators > Turn off ‘Select automatically’. If your only  your current network is listed you phone is likely to be locked.

If your phone is locked, you will need to contact your current provider and request to have it unlocked.