Compare checksums of the downloads with the ones provided by Microsoft
to verify integrity of files:
So you can be sure to receive clean downloads.
I agree there quite a risk to get malware infections when downloading
random stuff, especially if you go for torrents. However, Digital
River is hardly a random source. You'd get most products you purchase
from the Microsoft Store delivered by DR, so unless DR itself becomes
a victim of hacking, the downloads are safe.