Hi @Roopali Misal ,
In general, we would see this error if there is a policy in your subscription which disallows the creation / updation of such resources which are in your first exercise of AZ-900 learning material. To be able to proceed further, you might have to disable that policy which was not allowing the successful deployment. For more information w.r.t retrieving details about the policy that blocked your deployment, please refer this article.
If that's not the case then as the clean subscription / sandbox should work so there might be issue with the order of the exercises that you see in the AZ-900 learning material. If so, Microsoft Certification / Exam related questions are currently not supported on this forum. It's better to reach out to dedicated forum over here.