The account you used to post for help here has no subscription of any kind, not for Mac or iPad aside from your iPhone login troubles. Any Creative Cloud you have must exist under a different email address.
Please double-check the account email address you are successfully using for Lightroom Mac and iPad -- look in the application settings -- and use that same address when trying to sign in on iPhone.
If you need further help, please consider contacting Adobe Support directly. Visit https://helpx.adobe.com/contact.html, sign in, and then select the chat option.