Hi @Ramaswamy
Welcome to the Power Pages forum. It looks like your portal is in an "Inactive" state or you don't have an appropriate security role in the environment where your Power Pages site is created.
Check the following two options
1. Go to https://make.powerpages.microsoft.com/ and make sure you choose the right environment. Scroll down and see whether your portal is listed under "Active" or "Inactive" state. If it is active, step 2.

2. You should have a "system administrator" or "website owner" security role to the dataverse environment

Official URL: Click here
This should solve your issue.
If nothing works, then the best choice is to create one more site and try.
I presume it is primarily a permission issue.
PS: I believe you are using a developer environment to try power pages. If it is not you need an appropriate license to perform any activities.
Hope it helps.
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