TL;TR Log into http://www.icloud.com and agree to the terms.
It works. But there are some additional steps needed:
At work I tried with my new apple id: at work X[email protected]. At first It didn’t work even though I was able to access iOS dev center. I realised that it is required to access to http://www.icloud.com with such Apple ID and agree to the terms. After a few seconds I received a ‘Welcome to iCloud’ email to my work address and then I went back to the simulator and I successfully logged in.
BTW, for a personal account [email protected] I have for ages and use regularly it worked from the beginning probably because I have agreed to the terms a long time ago.
So not only @icloud.com of @me.com or @mac.com accounts work. All accounts work.