I can't create a new Apple ID

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

If you still need to set up iCloud with this Apple ID, contact Apple Support for help. 

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.

See this support article:--> If you see a Could Not Create Apple ID or Could Not Set Up iCloud message – Apple Support (UK)

Regards

Giulio