Welcome to Microsoft Q&A! Thanks for posting the question.
Sandbox is not supported in Microsoft Q&A. If you are facing issues in using sandbox while learning on Microsoft Learn, you can report sandbox related issues in the below document > Report feedback > Product or functionality > Sandbox issues
You can try changing your directory by clicking on your profile and then change the directory and select Microsoft Learn Sandbox.
Please ensure that you need to use your own personal account for the sandbox to activate As in the case of work account authentication and authorization is defined by your IT admin and hence won't allow you to activate/create paid resources (unless you are on the approved list) or free sandboxes. Try using your own Microsoft account. Create a new free account if you don't have one yet.
Sandbox Know issues: https://learn.microsoft.com/en-us/learn/support/troubleshooting
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