Hi,
From the log, it appears that there is not enough room in your hosting account to perform the backup.
Your Uploads directory is 9520.8Mb, and the account appear to reach capacity part way through this. You will need to clear out some space on your hosting account (or increase the available space). You will also need to delete the failed backup files, either through UpdraftPlus or FTP.
UpdraftPlus needs to write the backups to the server before it is able to transfer them. As such, there needs to be enough space available to write the backup files. In the case of Uploads, where the content may not compress much, this could mean you need at least the same amount of space again as for the original files themselves