Hi @Raj Patllola ,
If you've already confirmed that the credential of the administrator is correct, please run the following cmdlet to check if NTLM is present in the Authentication methods:
Get-WebServicesVirtualDirectory |FL
If the issue persists, please check if there are any network devices configured in front of Exchange servers. If so, try temporarily bypassing these devices and see how it goes.
Furthermore, you can read through the information provided in Scenario 3: Test-MigrationServerAvailability fails with 401 Unauthorized, Access denied or Invalid credentials for more possible steps you can use to troubleshoot the error.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.