Hi Ankit,Thank you for submitting your query on the Microsoft Q&A Platform.
We apologize for any inconvenience you may have encountered while attempting to access the sandbox environment.
Accessing the sandbox environment does not require any additional licensing. Please find the below steps.
Step 1: Please sign out from all active tabs within your current browser and clear the cache files. Afterwards, attempt to log in again using your learn ID credentials.
Step 2: Sign out from your current browser session and attempt to log in using an incognito or in-private browsing window.
Step 3: Utilize an alternative browser and attempt to log in once more.
Step 4: Test logging in with a new personal Outlook account within the learning path using a completely different browser.
Step 5: Attempt to access the sandbox environment using an alternate personal account to verify if the issue persists.
I have performed the above steps and am able to access the sandbox environment Please find the below reference screenshot.
If you are still facing any issue, please let us know in the comments. We are glad to help you.
If the information is helpful, please Accept Answer or Upvote so that it would be helpful to the other community members.