Since we last covered about Apple pulling the Walkie-Talkie app for security reasons we also mentioned that it was back with the latest update. We have seen some users still struggling to get it to work, so here is what you need to do.
First update your iPhone OS to iOS 12.4.
Update your Apple Watch to watchOS 5.3
You are now all set and ready to go, you will need your Walkie-Talkie contacts to update as well.
Contacts (Address book)
Go to your contacts edit the person your trying to use Walkie-Talkie and put the persons Apple ID as iCloud as shown below