i tried to register an icloud account for a friend on their mac, but when i try, ther is a message that inform that it has reached the maximum number of account registered from his mac.
I believe there is a three account limit on how many new accounts can be created per hardware device, so it sounds like this would be his fourth new account created. Does your friend have another iOS device they can use to create the account then go back to the Mac and enable it.