It appears to be hosted via S3 compatible object store. Their docs provide examples to browse/download via awscli or boto3 (as well as rclone).
https://source.coop/repositories/harvard-lil/gov-data/description https://source.coop/repositories/harvard-lil/gov-data/access
The link posted above by gdog05@lemmy.world (https://old.reddit.com/r/DataHoarder/comments/krx449/megathread_archiving_the_capitol_hill_riots/) has a magnet url that appears to be active still. It has ~1TB of data.
As well the link from pyr0ball@reddthat.com (https://capitol-hill-riots.s3.us-east-1.wasabisys.com/directory.html) has the same magnet link plus basic html index with all the files.