Here is a link to a tutorial reported by @bland328 for iCloud/AppStore/iMessage with general and detailed information, also valid for our VMs.   It seems my problem was related to something messed up in my System Preference panel, as I noticed that the error was related to it and moreover I was not able to add any account under "Internet Account". So, I deleted my administrator account and created a new one and after following all the advices in the tutorial I was able to login to
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