Choose several files after Upload and Secure Files encrypts and uploads them one at a time into the open folder. A file that cannot be uploaded is named, and the others continue.
Secure Files now counts toward your plan's storage. The bottom of the file list shows how much Secure Files uses, including Trash, and how much of your plan's storage is used in total. Delete forever frees space. An upload that would exceed your plan's storage is not started.