Hi Sanjay,
Thank you for contacting the community regarding your issue creating tenants.
As a security measure, creating tenants from existing tenants requires the tenant to be a paid subscription.
To confirm this is your issue you can open the developer tools in your browser and try create the tenant. you should see a 403 response saying "Additional tenant creation is not allowed without non-trial subscription"
If you want to create additional free tenants you can still create by signing up for a free azure account. https://azure.microsoft.com/en-us/free
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