Quite simple!

Navigate to Accounts → Groups and add the following groups.

GID	850
Name	qbittorrent
Samba Authentication	unchecked

Navigate to Accounts → Users and add the following users.

Full Name	qBittorrent
Username	qbittorrent
User ID	850
New Primary Group	unchecked
Primary Group	qbittorrent
Primary Group	qbittorrent
Disable Password	Yes
Shell	nologin
Samba Authentication	unchecked

Navigate to Storage → Pools and add the datasets and permissions. We’ll use default 755 permissions for all datasets.

Path	/mnt/vault0/apps/qbittorrent
User	qbittorrent
Apply User	checked
Group	qbittorrent
Apply Group	checked

Path	/mnt/vault0/media/torrents
User	qbittorrent
Apply User	checked
Group	qbittorrent
Apply Group	checked

Connect to TrueNAS via SSH or similar.

# Create jail
iocage create --name qbittorrent --release 12.2-RELEASE dhcp=1 boot=1
# Mount jail config dataset
iocage exec qbittorrent mkdir /mnt/config
iocage fstab --add qbittorrent /mnt/vault0/apps/qbittorrent /mnt/config nullfs rw 0 0
# Mount media dataset
iocage exec qbittorrent mkdir /mnt/torrents
iocage fstab --add qbittorrent /mnt/vault0/media/torrents /mnt/torrents nullfs rw 0 0
# Update packages
iocage exec qbittorrent "pkg update && pkg upgrade"
# Install qBittorrent without GUI
iocage exec qbittorrent pkg install qbittorrent-nox
# Enable qBittorrent service
iocage exec qbittorrent sysrc qbittorrent_enable=YES
# Configure config directory
iocage exec qbittorrent sysrc qbittorrent_conf_dir=/mnt/config
# Start the service
iocage exec qbittorrent service qbittorrent start

Navigate to http://DHCP:8080 in your browser and login with the default credentials.

Username	Password
admin	adminadmin

Navigate to qBittorrent menu and then Tools → Options… and change the Default Save Path to /mnt/torrents:

There we go!

From there, you’ll just have to create a SMB share using the created folder.

I just got the interesting part from here.