The article also includes tips on using the app.
Who better to recruit than people you already know?
you could search for and follow people using their email addresses located in youraddress book.

SelectMore>prefs and Privacy>Privacy and safety>Discoverability and Contacts.
Turn onSync address book contacts.
Turning off sync later won’t remove contacts you’ve already uploaded.
Grant the app permission to access your contacts if necessary.
It doesn’t hurt to try, though.