Hello Deepak T
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
Based on the error message you have shared, you are running into an issue with exceeding the approved quota for the standardDASv5Family cores in the eastus region. To deploy Azure Virtual Desktop, you need to have enough cores available in your subscription.
You can request a quota increase for the standardDASv5Family cores in the eastus region by following the link provided in the error message. Once you have requested the quota increase, you will need to wait for the request to be approved before you can deploy Azure Virtual Desktop.
Hope this helps.