"The iCloud terms of service have changed"

I bought a new MacBook Air. On startup, It asks me for a password to my iCloud account (I had a MacBook Air previously). After entering a password, I get a red ink message "The iCloud Terms of Service have changed" and I cannot go further. There's no a possibility of accepting the new terms of service. I cannot accept the new terms of service on my old Mac Book Air (el Capitan), because I don't see them anywhere, despite the fact I can log into my iCloud account from there. What can I do? Please, help.