You're using too much product. An iPad is a pretty small area for one spray of product.
With all due respect, this product has been around since 2007, and if it wasn't a "true WOWA" you wouldn't have been the first one to figure that out. There is a small learning curve to this product, i.e. how much to use, how far to spread, in order for it to behave in the expected fashion. And it's pretty simple, you just need to get the product spread out thin enough to be able to "walk away". If you are using too much product for the surface area you have, you will be unable to get it spread to the required "thinness", and then it will leave residue as you are experiencing.
There's a few (tens of thousands) of us who have been able apply this product without incident; you simply need to adjust your technique. Maybe try it on your car?