Guide to create an FTP user on CentOS 7.
If no FTP server software, install vsftpd.
yum install vsftpd
adduser -c 'SFTP USER_USERNAME' -m USERNAME
passwd USERNAME
chown USERNAME:USERNAME /sftpuser/folder
Make sure vsftpd.conf is properly configured:
vim /etc/vsftpd/vsftpd.conf
anonymous_enable=NO
local_enable=YES
write_enable=YES
chroot_local_user=YES (prevent access outside home directory)
service vsftpd restart
usermod -d /sftpuser/folder USERNAME