You don't have to attach your phone, just a alternate email address. You can also answer security questions I think. Personally, this is exactly why I use a gmail account for my own stuff.
to answer questions, I was not running a VPN. So it was someone trying to force their way onto my account but gmail slapped them. meh when running a vpn I have not had any problems with getting the error. and no you dont have to turn on the "perk" its part of google security feature. if someone tries to access your account from a suspious location gmail will block them, and you will get a notice saying someone tried to access your acct. (red activex bar) you will then be prompted to a page showing the info i posted.