I just bought one of these things on eBay and had to figure this out all on my own.
First, you need to install the OS on the NAS. Then you need to visit the Web interface for it and do a couple of things.
Be sure to apply after each one of those. I could not believe FTP was enabled by default. Hellooooo Ransomware!
sudo apt-get install samba smbclient cifs-utils nmap samba-common
sudo nano /etc/samba/smb.conf
#add min and max lines below
; bind interfaces only = yes
client min protocol = SMB2
client max protocol = SMB3
#exit and save
sudo systemctl restart smbd.service
mkdir ~/tnas
mkdir ~/bin
nano ~/bin/mount-tnas
#add the following line, exit and save
sudo mount -t cifs -o uid=$UID,gid=$(id -g),vers=3.0,username=your-user-name-on-NAS '//NAS-ip-address/your-private-directory' /home/your-user-name-on-ubuntu/tnas
chmod +x ~/bin/mount-trans
If you did not already have a ~/bin you should probably log out and back in. Then open a terminal and type
mount-tnas
You can forget about being able to mount this thing through the GUI file utility. Ubuntu is always quite a ways behind when it comes to things like that. This will mount it on demand and make it appear in your GUI file manager.