As an action of publishing a printed version of your content, you already own the copyrights to your book, as per Indian Copyright Laws. Also, a Free ISBN is allocated to your book upon approval of your submitted book on the Notion Press platform which copy-protects your book. Notion Press does not have any paid publishing services under the program at the moment. However, if you want to apply for a government registered copyright to protect your content in case of a legal dispute, you can do so by yourself.
Read more about the difference between owning copyrights and copyright registration here.