How to correctly issue FTP access?

Question

linux

There is Ubuntu 18.04 in which I:

• closed root access
  
• disable password access
  
• enable ssh access
  
• created two users, one in the root group, the other in the www-data group
  
• site files are in /var/www/html/*
  

There was a task to issue ftp-access to the third-party specialist. How to act correctly?
Enable password access and create a new user by connecting it to the www-data group?

Answer 1

+ chroot in ftp config for given user
and home directory for given user /var/www/html/
for vsftpd include in /etc/vsftpd.conf

# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
chroot_list_enable=YES
# листинг пользователей без ограничений
chroot_list_file=/etc/vsftpd.chroot_list

by the way and what for ftp if there is a full-fledged ssh??
mount via sshfs and something.

Answer 2

you need to give read and write permissions