First check the obvious and make sure you are flashing the correct AOSP ROM for the Sprint Note 2 aka SPHL900.
If that's all good then you might need to start over and odin flash the stock MC2 with flash counter reset (found in development forum). After that use the Note 2 ToolKit found in original development forum and reroot your phone with it. At the same time you will also need to make sure you choose the ALL IN ONE (root, insecure boot image & recovery) option. Once you complete this you will want to immediately flash a current recovery such as Phil's 6.07.9 so have that zip already on your memory card before you start anything. Once you have a current 4.3 compatible recovery then reboot the stock rooted MC2 and immediately go to dialer and dial ##72786# to do a hands-free activation. This will ensure all your phone's provisioning is done before going to a different rom. Once that's done you can flash your rom of choice. Done
FYI: AOSP ROMS have specific instructions for install and initial setup so follow the OP's instructions. Also you must SKIP the phone activation portion upon initial setup of some AOSP ROMS. I just wanted to point that out in case you didn't know.