I'm using KDE plasma and in the notification aera there is something to check the disk quota, when I click on it, I've got this:
It's in French but it says:
Unable to find tool "quota"
Thanks to install "quota"
After some investigations, I've found it's quota-tools which is needed. Some distros already have it packaged, I didn't find it in Solus repo.
Here the website: https://sourceforge.net/projects/linuxquota/