Make sure, that you have user quota (uqota) and project quota (pquota) set as options on the chosen mount point in /etc/fstab. For example:
/dev/vdb1 /var/backup xfs noatime,uquota,pquota 0 0
=== 32-bit Project Identifier Support
We need to enable 32-bit project identifier support (PROJID32BIT feature) for our naming scheme (uid numbers larger than 65'536):
umount /var/backup/
xfs_admin -p /dev/vdb1
writing all SBs
versionnum [0xb4e4+0x8a] = V4,NLINK,QUOTA,ALIGN,DIRV2,LOGV2,EXTFLG,MOREBITS,ATTR2,LAZYSBCOUNT,PROJID32BIT
=== Verify ===