Troubleshooting Microsoft Office 365 problems

SharePoint Tenant Configuration Failed with 401 (Unauthorized) or 403 (Forbidden) errors

Cause: This error occurs when certain app authentication are not provided.

Resolution:

Login to your SharePoint admin portal by navigating to https://[tenant]-admin.sharepoint.com
Navigate to Policies > Access control.
Click Apps that don't use modern authentication
Esnure Allow access is selected. If not, select it and click Save. Refresh the page to ensure the change has taken effect.

Download and install SharePoint Online Management Shell by following the steps listed here.
Connect SharePoint Online Management Shell with your SharePoint Online environment by following the steps listed here.
After successfully connecting with your SharePoint Online environment, run this command.

Set-SPOTenant -DisableCustomAppAuthentication $false

Wait 15 mins for the changes to take effect and try adding the tenant again in RecoveryManager Plus.
If the issue still persists, contact support@recoverymanagerplus.com.

Cause: This error occurs when sign-in for a particular mailbox is blocked and the product attempts to backup or export that archived mailbox.

Resolution:

Please enable sign-in for the mailbox and try running the backup/export operation after sometime.
If the issue still persists, contact support@recoverymanagerplus.com.