Lately, when I open the software, it keeps downloading and I don't know what it is downloading. It has downloaded 379GB and uploaded 77.67GB in the last week.
There's nothing showing there that would account for network traffic. Are you sure there was network traffic while that was running? If so, does this still happen if you disable all third-party plugins?
Upgrade Storage
I am also having issues with not being able to upload to Box.com WebDAV. Maybe it's somehow related to the webdav issue? I have mentioned the webdav issue in another discussion (https://forums.zotero.org/discussion/97249/how-to-force-trigger-sync-for-specific-item-attachments-when-using-webdav). The report ID of that issue is: 1739292714