The animation sprites for these creatures don't respect a single aspect ratio. The sprites that are going down (bottom left and right) are more narrow than the ones going up (top left and right).
Its impossible to use these without the images getting stretched unless there is a way to dynamically change the animator to adapt to each image having its own width x height mix but that's just silly.
I will happily pay for assets but this is a little outrageous in my opinion.
I bought this pack and I would like to receive correctly sized images, or my money back