I'm trying to set up my iCloud account on my new laptop, but I don't know what my 4 digit security code is

I just got a new laptop, and I'm trying to set up my iCloud for it, but I don't know what my 4 digit security code is. I have been trying the passcode for my phone, but that just leads to a 6 digit code being sent to my phone which I type in. This only leads to a message saying that my security code is incorrect. What do I do?