Thanks for posting your question in the Microsoft Q&A forum.
There are a few steps you can take to troubleshoot the issue:
- Ensure that you have a stable internet connection
- Clear your browser's cache and cookies, then try activating the Sandbox again.
- If clearing the cache doesn't work, try accessing Microsoft Learn from a different browser or device.
- Double-check that you're signed in with the correct account credentials on Microsoft Learn.
- Visit the Azure status page to see if there are any ongoing service issues affecting Sandbox activation.
If none of these steps resolve your issue, it's possible you've encountered a limitation with the Sandbox, and you may need to try addressing it later.
Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful