WhatsApp not working on my iPad not even web based

Some websites fail properly render correctly (if at all) when iOS/iPadOS Safari User Agent is used in one or other of its browsing modes - of which there are two - these being Desktop and Mobile.

It’s easy to switch between modes if a website isn’t functioning correctly. From the desired web-page, touch the aA icon at the left of the Address Bar; this will reveal a menu. From the menu select Website Settings, then select (or deselect) Request Desktop Website, then tap Done. Now refresh the webpage.

The chosen setting will be saved for the selected website - and can be simply reversed if needed.

The WhatApp developers have not released an App compatible with iPad - the App being currently limited to iPhone.

Whilst the App is not available for iPad - you should be able to access the service using a web browser:

https://web.whatsapp.com/

If you are unable to use the WhatApp web portal, your iPad may simply too-old to have a supported web browser.

You make no mention of your iPad model or installed version of iOS/iPadOS. This information can be found here:

Settings > General > About

With iPadOS 15.1 installed, you would be well advised to update to the most recent version; at the time of writing, iPadOS 15.2 is current.

If you continue to experience difficulties, please provide a screenshot of any errors that you see.

As already stated, Safari on your iPad can be used in one or other of its two browsing modes - these being Desktop and Mobile. You can switch between browsing modes using the provided instructions.