Can not back up due to file exists

Hi updraft team,

I have tried to back up my website, japan-hana.com/en

But it keeps showing me the following message.

WORDPRESS MESSAGE:
Backup directory could not be created…
The folder exists, but your webserver does not have permission to write to it. You will need to consult with your web hosting provider to find out how to set permissions for a WordPress plugin to write to the directory. (/public_html/en/wp-content/updraft)

So I also tried to delete this specific folder from ftp, it still does not work.
Then I deleted the whole plugin, and reinstall, and the same problem happened again.

Please advise what I do. Thanks!

The page I need help with: [log in to see the link]