Hello Joyant,
Welcome to the community!
Sorry to hear you are not able to set up your WhatsApp. I understand you obtained a new phone number. However, most phone numbers are recycled since it is not possible to provide new, unused numbers for every new customer or number change. Generally, cancelled numbers are not re-assigned for a specified period to try to prevent issues with old owners of the number.
Unfortuntely, it appears as the old owner of that phone number was banned from WhatsApp. However, you should be able to remove the ban. WhatsApp are aware there can be high phone number turnover (see here). You would need to contact WhatsApp and inform them that you are the new owner of the phone number (see here). They may require you to provide documentation that you just recently obtained the phone number, though.
Alternatively, you might consider changing your phone number. You should be able to do so via your My Account --> Usage & Services --> Mobile. From there, you can find the option to Change my number (under Quick actions, near the bottom of the page).
While there is no guarantee you won't have similar issues with a different number, I think it's unlikely a different number will also be 'banned' in WhatsApp.
Hope this helps 😀
Cheers
