Issue Updating to 4.9.8

Hi there,

I have a client whose website I’m re-designing. I’ve logged into her account and I tried to update her website but it keeps saying “installation failed’ and gives me an error message:

Downloading update from https://downloads.www.ads-software.com/release/wordpress-4.9.8-no-content.zip…

Unpacking the update…

Could not copy file.: wordpress/wp-includes/css/customize-preview-rtl.min.css

Installation Failed

Now every time I try and update it the file that it couldn’t copy always changes. At first, it couldn’t copy “wordpress/wp-includes/functions.wp-styles.php” now it’s a totally different file!

Please help! ??

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