So you created your VPS and  installed directadmin ok. You can read the full documentation here based on file system type. For ext4

Start by editing

# mount | grep ' / '
# /dev/sda2 on / type ext4 (rw,noatime,quota,usrquota,grpquota)

This shows ext4 as file system type and confirms our mount point is “/”

add usrquota,grpquota to "/"
# nano /etc/fstab
UUID=87dc142a-1e3a-4232-b5cb-e46a7ef50873 /                       ext4    defaults,noatime        1 0
UUID=75f14d25-640a-4131-999d-e7196fc53d11 /boot                   ext4    defaults,noatime        1 0

Remount the partition

# mount -o remount /
# /sbin/quotaoff -a; /sbin/quotacheck -avugm; /sbin/quotaon -a;