Sudo vi /etc/ssh/sshd_config

Subsystem sftp internal-sftp
Match group Group-A
    ChrootDirectory /Group-A
    ForceCommand internal-sftp
    AllowTcpForwarding no

Match group Broup-B
    ChrootDirectory /Group-B
    ForceCommand internal-sftp
    AllowTcpForwarding no

sudo useradd Group-A-Users
sudo useradd Group-B-Users
sudo passwd Username
sudo usermod -G Group-A Group-A-Users= All users that belong to this group
sudo usermod -G Group-B Group-B-Users= All users that belong to this group
sudo mkdir /Group-A
sudo mkdir /Group-B
sudo mkdir /Group-A/Upload
sudo mkdir /Group-B/Upload

sudo chown root /Group-A
sudo chown root /Group-B
sudo chmod go-w /Group-A
sudo chmod go-w /Group-B
sudo chgrp GroupName /Group-A/Upload
sudo chgrp GroupName /Broup-B/Upload
sudo chmod ug+rwX /Group-A/Upload
sudo chmod ug+rwX /Group-B/Upload

sudo nano /etc/ssh/sshd

PasswordAuthentication yes

Match Group sftpusers
ChrootDirectory %h
ForceCommand internal-sftp
AllowTcpForwarding no

sudo useradd bob
sudo passwd bob

sudo groupadd sftpusers
sudo usermod  -g sftpusers bob
sudo usermod -s /usr/bin/rssh bob
sudo usermod -d /home/bob bob

sudo chown root:root /home/bob/
sudo chmod 755 /home/bob/
sudo mkdir /home/bob/uploads
sudo chown bob /home/bob/uploads

sudo service sshd restart