Hi @AkshayDave-6636
We are sorry to hear that you're experiencing issues with activating the sandbox.
Please try following steps:
1.Log out from all Microsoft accounts in your browser and try signing in with your Learn id.
OR
2.Try to login to your Learn account in a new incognito window or new private window.
If you are still facing the issue, please don't hesitate to reach out to us.