Nighthawk CAX80 security key required for device logon

I have a Lenovo Thinkpad from work that I use from home when I need to work remotely. I needed to update my password, but when I tried to log on to my home Wi-Fi network with the laptop I am now required to enter a network security key. I am not sure how to find that information. I have my router’s MAC, serial number, password, etc. but not a “security key.” Can anyone provide guidance? Thanks!