Confused

Creative Cloud doesn't use serial numbers.

Does your computer meet the minimum requirements for the apps you want to download?

1st, Log-in to your account and click this link https://account.adobe.com/products to see what you bought

Cloud Manager to install all programs https://www.adobe.com/ie/creativecloud/desktop-app.html
https://community.adobe.com/t5/get-started/how-to-activate-your-adobe-software/td-p/9636861?page=1

A subscription does not use a serial number

To Cancel https://helpx.adobe.com/manage-account/using/cancel-creative-cloud-subscription.html
-or Chat link https://helpx.adobe.com/contact/support.html

-click the chat icon at the bottom right of the page to open a chat session
-the chat icon looks like '3 dots inside a circle' at the lower right
-type AGENT into the chat window to connect directly to a person rather than the AI
.
Also - beware of answering anyone who sends you a private message
https://community.adobe.com/t5/community-help/avoid-phishing-3-easy-ways-to-identify-adobe-staff/td-p/10791730