I think there's no reason to be afraid of a virus.
What's not clear is where the artwork came from, and she/he has not answered questions about that. Some look like Disney designs and for those you need a license to digitise them - and Brother is the only one that has a license. So it would be illegal to even download them let alone use them.
for me do not worry. They are unzipped and so there can be no virus. They are lovely design and just enjoy the generous gift. Do not forget to print the colour sheet