Sorry about that. You took a first month free, cancel free of charge during the free period annual subscription. You did confirm that you have read and accept the terms and conditions. You entered your credit card details. Each time you enter your credit card details, you need to know, that at some point some money will be withdrawn. So it can't be that you only took a free one month subscription. The cancellation fee is not the entire remaining due, but half of that as stated in the conditions. During the first 14 days of your first paid month, you still had the opportunity to cancel free of charge.
All this said, you should contact Adobe customer care and see if there is any possibility to get out of your contract with minimal fees. Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. If the chat window fails to open, or is non-responsive, use a different device to start the interaction.
(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
https://community.adobe.com/t5/account-payment-plan/how-to-contact-adobe-support/td-p/11843852)