Hello Praneeth kumar,
Thank you for posting your query in the Microsoft Q&A Community.
Please be informed that the free trial Subscription is a one-time offer for new customers who haven't signed up for Azure in the past.
Receiving this error message indicates that some or all the details provided already exist. If you are sure you haven't signed up before, someone else might have used your information (most especially your card) to complete the same process in the past.
You can also take a look at the common issues that could have caused this by following this link https://learn.microsoft.com/en-us/azure/cost-management-billing/troubleshoot-subscription/troubleshoot-azure-sign-up#about-you
Let me know if further assistance is needed.
Babafemi