Select the three small character icons at the bottom right corner of the screen to join a team. While you're in a team, you can request 5 free lives from team members every 3 and a half hours in the chat section.

 

To use the free lives, follow these steps:

 

On the "Home" screen, select the heart-shaped icon at the top of the screen.Then, check the "Free lives" section.

You can also provide free lives to players in your team in the "Team" section of the "Chat" tab