The best way to get Photoshop for iPad is by using a bundle package that includes the desktop version of Photoshop.
You can get Photoshop for iPad and desktop here: (affiliate link)
https://bit.ly/ipadphotoshop
With every Adobe Photoshop membership, you can also get the iPad version. Every project on the iPad version of Photoshop will get saved on the cloud and you can access it on the desktop.
You can also get an Adobe Creative Cloud membership that gives you access to 20 plus Adobe applications and you will get Photoshop for iPad as well.
*Disclosure: Keep in mind that some of the links in this post are affiliate links and if you go through them to make a purchase I will earn a commission. I link these companies and their products because of their quality and not because of the commission I receive from your purchases. The decision is yours, and whether or not you decide to buy something is completely up to you.
I do not work for Adobe and this video is for educational purposes.