Ensure and cross check if you are creating the resource only in Learn sandbox subscription and resource group. If you are doing that, then it's free. It will just show you the price but won't charge you.
When you perform the exercise, you activate the sandbox and should login to portal using your person @Karima ben or @harsh.com etc. Microsoft Id and not @whatevercompany.com id.
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Please don't forget to Accept Answer and Up-vote if the response helped -- Vaibhav