I was working on an older mac book and at the re-installation screen and was asked for apple id and password.
Then I was presented with an error, "Unavailable" something to that effect.
So, I googled!
Google informed me that this was due to the apple id never being tied to the mac book/OS
The work around was to open safari and sing into icloud which was not possible as the version of safari was too old.
I have yet to find a work around for that, does anyone have a solution?