It may be the case that your HZ02 library keeps disappearing from the libraries pane each time you load up Kontakt.
Please close Kontakt, go to https://www.native-instruments.com/en/specials/native-access/ and download "Native Access"
Launch Native Access and log in with your Native Instruments login. You should then find that the next time you launch Kontakt HZ02 will remain after you have added it.
If that does not work or you are using an operating system that does not support Native Access, follow these instructions:
Completely close all instances of Kontakt and look in your HZ02 folder. In there, find the file called 'HZ02 Percussion.nicnt' and rename this file to 'HZ02 Percussion.old'.
Open up Kontakt and try adding HZ02 to the library pane again. Upon closing and re-opening Kontakt, you should see that HZ02 has stayed.
If this doesn't seem to have helped, delete the files in that folder with "info" in the name and rename the "HZ02 Percussion.old" file to "HZ02 Percussion.nicnt"
If you are still having issues, please contact our support team with a screenshot of your HZ02 folder.