To use ContactBook for your G Suite account, Your organization G Suite Administrator needs to do following.
Once installed you will be redirected to ContactBook website. If not, go to the link given below. Click on LOGIN button on the top right and provide required permission access to manage contacts for your domain.
You will be able to see your existing labels and contacts of your Google Contacts in ContactBook app. Open Google Contacts in another tab and manage contacts and labels in Google Contacts and then click on SYNC on ContactBook interface so that all your contacts and labels will be reflected in ContactBook. Once all updated, you can share each label with G Suite users of your choice :)