To install HPLIP you will need the root and/or superuser password.

Depending on your Linux Distribution the root password is either set during install--or the password is the same password as your user account.

For example, on Ubuntu the root/superuser password is normally your user password--however on Fedora the root password is usually set when Fedora is installed on the system, therefore the password might be different than the user password.

You may want to contact your Linux Distribution for more information on using the root/superuser account.