HI, WHAT SHOULD I DO TO ACTIVATE ICLOUD?

Maximum limit for creating Apple ID from the hardware address of iphone is three , you can't create more Apple ID accounts , however again sign in with your same Apple ID and it's account credentials ( in fact you have signed out the Apple ID ) in the empty fields or sign in with another apple id that was created from another Mac / iPad or different iPhone .

See the article 

Sign in with your Apple ID - Apple Support