When I try to sync the file in Zotero, there is an error that says the storage is not enough. however I have updated the storage, and only use 8.7% of the storage.
You wouldn't be getting an error for your own library. The owner of one of the groups you're in is at their file storage, so you might be getting an error about that.
In any case we'd need to know the exact error message that you were receiving.
But when I click to create a new group library, it will automatically link to this online account. That's why I think I use the same account online and locally.
In any case we'd need to know the exact error message that you were receiving.
If you'd like us to transfer your storage subscription to another account, email us at storage@zotero.org with details.