D-Link ShareCenter DNS-320 User Manual page 107

Section 4 - Configuration
Step 7 - Edit the amount of space you want to assign to the
group for each volume. Enter zero to give unlimited disk space
to the group.
Click Next to continue.
Step 8 - When editing the quota, make sure the size is not
smaller than the user quota on his/her account.
Click Yes to change the quota.
D-Link ShareCenter DNS-320 User Manual 103