The most common occurrence of the “Destination folder already exists” error is during a theme or plugin installation. The error is due to WordPress extracting the plugin or theme's zip file to folder with the same name as the archive file.
When the error occurs, you’ll find the plugin or theme installation terminates. To resolve the issue, the first step is to check to see if the theme or plugin is already installed. If so, a folder will already exist on your server, which will cause the error.
You can choose to uninstall the plugin/theme and attempt reinstallation, or head to cPanel File Manager to remove the folder manually.
1) Log into your cPanel account.
2) Go to Files > cPanel File Manager to view the files and folders are stored on your server.
3) Navigate to your WordPress folder then enter the wp-content > plugins folder if the error is occurring during a plugin installation, or wp-content > themes folder if you’re unable to install a theme.
4) Find the conflicting folder, select it and click Delete to remove the folder from your server. You can now proceed with reinstallation.
If you still notice any problems or if you need any help, please open a new support ticket.