ArcGIS for Personal Use Subscription?
Please refer the steps in How To: Create an ArcGIS Online Organization and access ArcGIS Pro after purchasing a Personal Use s...
You can activate ArcGIS Online from My Esri > My Organizations > Transactions.
You may also log a case with Esri Technical Support to guide you through the installation process (included in your subscription), if required.
I see. You must have received an email from Esri with Order Fulfillment Confirmation. The mail will consist of a link to My Esri Fulfillment Page.
Copy the URL and paste in the same web browser in which you are logged in to My Esri. This page will consist of some drop-down tabs.
Do you see the option to activate your ArcGIS Online?