I pay for unlimited storage. Still receive "You have reached your Zotero File Storage quota. Some files were not uploaded. Other Zotero data will continue to sync to the server." When I open Account Settings, "Current Usage" in my library (and total) says 0 MB despite at least 6 GB of PDFs successfully uploaded (and verifiably synced to other devices). Ignore the warning?
You're syncing with a different account. You can just click on Web Library at the top of this page to see that you have an empty library in this account.
Check the Sync settings on your syncing computer to determine the account you're actually syncing with and then email storage@zotero.org to request a transfer of the subscription.
Upgrade Storage
Check the Sync settings on your syncing computer to determine the account you're actually syncing with and then email storage@zotero.org to request a transfer of the subscription.