The maximum of free accounts have been activated on this iPhone . Why?

See -> If you see a Could Not Create Apple ID or Could Not Set Up iCloud message

If you see a Could Not Create Apple ID or Could Not Set Up iCloud message - Apple Support

BTW:

You are sign in here .  .  .  with your Apple ID & Password.

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

What happens when you use the same Apple ID & Password that you use to sign in here?

See -> Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support

If you still need help, get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK)