Thanks Joao! Yes, we chose our varieties for their hardiness and disease resistance. I spent a LONG time finding ones that should be resistant to cedar apple rust, which we know is on our property.
The nursery owner replied and said these are actually scale insects and "much easier to deal with than aphids." I am not convinced since I am seeing pictures of woolly aphid damage that look exactly like what my trees have, but whatever - they are a pest nonetheless.
I will be getting some dormant oil and Neem oil per her suggestion, having scrubbed off the insects in the meantime. I also plan to put in some plants around the trees to attract those good predator insects
Honestly though, I am still going to request a refund for the tree with FOUR damaged spots. It's pretty annoying to have brought home 2/2 trees at a premium price that already have an infestation/damage...