Adobe Creative Cloud Plan

There is NO FREE subscription that actually allows you to use any Adobe program for more than 7 days and then you automatically are enrolled in the Full Price Subscription plan.

Could be you used some Adobe programs that were provided by your school last year and now you need to pay for this year.

Contact your school for details.

If you had purchased the plan then just signing out the account is not enough to stop future payments, you need to cancel your subscription. Look at the following link for information on how to cancel your subscription.
https://helpx.adobe.com/manage-account/using/cancel-subscription.html

Now that your account is charged you should also look at the following to see if you are eligible for a refund or not. 
https://helpx.adobe.com/manage-account/using/creative-cloud-subscription-terms.html
If the information does not help, then you need to contact support.
Login to your account and navigate to the URL below. Make sure that the browser has cookies enabled, and all script blockers are disabled.
https://helpx.adobe.com/contact.html
Click on the chat icon on the bottom right, and type AGENT to avoid bots and talk to a human.
Also, be mindful of answering anyone who sends you a private message. See the following for more information about scammers
https://tinyurl.com/y7cfrr7y
-Manan