Sysadmin add new ftp user ?

what for ?

you can't setup pure-ftpd virtual ftp user at that location if you want nginx to access/read files as it has to be owned by nginx user/group which /home/username won't be.

you could setup regular linux user account for sftp native access but would allow wider access to the user if you don't know what you're doing i.e. Linux Basics: How to Add and Delete Shell Users on CentOS which gives added user ssh and sftp access

you'd be on your own for support/troubleshooting or members may help but I wouldn't provide support as Centmin Mod is provided as is