You might need to double-check if it's really a Samsung Galaxy Note 4 from Verizon because it should be automatically unlocked to use with Cricket.
If your model number is anything other than Verizon, then you need to unlock the phone. Not all phones will ask for unlock code, only for those AT&T and Cricket. But if the phone is T-Mobile or Sprint, the best way to unlock it is by far via USB remote cable.
You can use third-party websites like miliunlocks.com to unlock it, they unlocked the phone for me in under 10 minutes.