How To Set New User SFTP Permissions Restricted To WordPress Uploads Folder

As I follow along “How To Enables SFTP Without Shell Access on Ubuntu 18.04” I was able to achieve exactly as shown in the tutorial. That is:

1. Create a new user “sammyfiles”
2. Create a folder “/var/sftp/uploads”
3. Give “sammyfiles” permission to upload files to “/var/sftp”

However, after replicating it exactly like this:

1. Create a new user “sammyfiles”
2. Create a folder “/var/www/html/wp-content/uploads/csv”
3. Give “sammyfiles” permission to upload files to “/var/www/html/wp-content/uploads”

I was unable to achieve the ability for sammyfiles to access the folder. It always gives me the following error:

packet_write_wait: Connection to 127.0.0.1 port 22: Broken pipe

I need a new user to be able to upload content directly to the WordPress uploads folder only - nothing more, nothing less.

The issue seems to be that of setting permissions. Any help would be GREATLY appreciated as my business depends on this feature.

Thanks in advance.