icloud drive keeps turning off

I am trying to reinstall an app (whatsap) and it keeps telling me that to restore I need to turn on icloud. Sometimes it turns itself off again after 30 seconds and sometimes it doesn't but still won't let me restore the whatsap. I have updated the itunes, the account is linked and has a card attached to it. I have uninstalled and reinstalled the app. I logged out of apple id and logged back in, did the merge as suggested in another post. I have restarted the phone also. Nothing is working.