Apple ID keeps prompting on iMac

I have had to recently blow away and start from scratch my Mac OS - I am just getting back in, and when I go to iTunes or App Store, i get prompted for my AppleID - I enter it, and it prompts again. I have changed the ID, restarted the Mac and same issue - I get it where it says to enter the ID and passcode. I get the passcode on my phone but when I enter the password on the Mac, it does't prompt for the passcode - what am I doing wrong... in a loop from ****