How do I get contact list in App Inventor

what about reading the complete thread of the extension to not find only the documentation, but also a few examples how to use the extension?

It Will Return Two lists of name and number with its same index.

EDIT: it seems to be, the lists are not in sync, see also [Extension]ContactList - Get All Contact List - #32 by shashank - Extensions - Kodular Community
unfortunately only the developer of the extension is able to fix that, you might want to send him a PM in the Kodular community...

Taifun