the files.balena-cloud.com downloads are now fixed
curl does not follow redirects by default, you need curl -L for that
what file are you trying to download? The curl link you posted there wouldn’t give back anything, as those folders can’t be listed / can’t do recursive downloading. For example the unconfigured OS image for the NUC for that version is at curl -L -O https://files.balena-cloud.com/images/intel-nuc/2.13.6%2Brev2.prod/image/resin.img.zip. Also notice, that + is URL-encoded in the link, in your example not sure how you got that link
If you provide us with some more info of what are you trying to download, we are happy to help further!