Officially Box Sync client for Linux does not have and has no plans for development because it is not a priority. Although this method can assess alternative.
First of all you need to install the davfs2 package. You can do this by issuing the following command in terminal: (or you can also use your favorite package manager to install WebDAV)
sudo apt-get install davfs2
sudo adduser username davfs2
Now you should create a dedicated box.com folder.
echo "https://dav.box.com/dav /home/username/box.com davfs rw,user,noauto 0 0" | sudo tee -a /etc/fstab
sudo chmod u+s /usr/sbin/mount.davfs
Now you have to switch to a regular system user. This can be accomplished by issuing the following command:
Next you should disable the file locks in your davfs2 configuration file, insert your box e-mail and password, change the privileges to the secrets file containing your credentials and finally to mount your account:
echo "use_locks 0" > ~/.davfs2/davfs2.conf
If this command gives you "No such file or folder" error, just create the folder and file with the command below
then proceed with these commands.
echo "https://www.box.com/dav box_email box_password" > ~/.davfs2/secrets
chmod 600 ~/.davfs2/secrets
Initially it may take some time in order to synchronize all of the files in your box with the newly created folder but after that you should be able to create, delete and overwrite all of your files.