I have an older Mac Pro on OSX Mavericks that I would like to stay on Mavericks because of certain software comptability (like Aperture). The strange thing is that if I -for example- want to perform an software upgrade it comes with the iCloud login message box and when I enter my credentials it wants to perform a two factor authentication (and I see the 6-number code show upon my iPhone). Problem is however that I don't see a box or field to fill in the 6-number code. I think this because OSX Mavericks was still before this type of authentication. So now I'm in tricky position that I can not perform any upgrades... Anyone know how to handle this??