Installing HP Printer on Crouton, HPLIP says CUPS is missing
Solution 1:
To start the service execute:
sudo /etc/init.d/cups start
it worked for me
Solution 2:
I had the same problem, and I resolved it just by running the Cups service:
service cups start
It looks that the HP install script is actually checking if the service is started to infer if the package is installed.