How to get a sequence of images to play out on a plane.

I have rendered a folder of images, and would like to learn how to get the to play out as frames on a plane.
I’ve changed Image Source to Image Sequence and it seems to work some of the time but I am seeing the plane when I only want the alpha images on it.

Does anyone have any advice or a tutorial link for this please?

(settings only in .blend, images wouldn’t pack)

It’s basically cropped screengrabs of the viewport smoke, because that wouldn’t render at all on my computer. Ultimately it’s to be a puff of smoke in another animation.