You need to clear out some space. I would recommend running the following commands if already booted.
If you need to boot first, boot into Advanced Options for Zorin then select the (recovery) option and then arrow key to Drop to root prompt (This avoids adding any new files to root when you boot).
sudo apt clean && sudo apt autoremove
Clear out old logs:
sudo journalctl --vacuum-size=200M
You may need to remove old kernels.
What is your terminal output for
dpkg --list 'linux-image*'