How to setup Disk Quotas on macOS Big Sur?
You would need to install quota-tools from Homebrew and then use that to configure your disk quotas.
Install Homebrew (if you haven't done so already)
/bin/bash -c &quot;$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)&quot;

Then install quota-tools.
brew install quota-tools

Afterwards edit your /etc/fstab to enable disk quotas for the file sytem
/dev/rdisk0 /home apfs defaults,usrquota 0 2

Then run edquota to add disk quotas for the individual users:
sudo edquota -p user1 user2

After that restart the system to have the disk remounted and disk quota to take effect.