I also have this issue with a brand new iPhone I bought and being a new Apple user. The moment I was configuring my phone, I had to create a new Apple ID. I have done this just to find out the next day they have locked my account, the reason is anyones guess.
This is the second time it happened two days in a row, ridiculous. Had to call the Apple Support to get my account reactivated. I asked them what the reason was. but they were not able tell me the reason why it keeps deactivating, the usual script they keep telling people: "Did anyone else use your account etc..".
The worse part, they are not able to reactivate your account because they can't or they won't due security reasons maybe, I don't know, but instead have you to wait 24 hours to get it activated again leaving your phone partially unusable at the moment.
The last person I spoke to, said that I may have to create a new Apple ID, but you won't be able to sign in with the new Apple ID, because you are not able to sign out of the locked one, it keeps asking for a password and after entering, it says: "This apple ID is not active". Correct me if I'm wrong, it's my first time using Apple products.
To call them, you can head over to https://getsupport.apple.com/solutions/call and pick the topic regarding this issue.
