Help me! I have a Q about BR in h1z1

So b asically we are 3 friends and 1 of us does not have h1z1 yet. He will only buy it if it is possible to play together as a team of 3 in BR?? I know it's possible to do 2 as a team and the i got confused.... when you select to play as a 5 man team does it need to be filled up or is it able to only be 3 in the team?? Or do you have to be 5 to be able to start the game. TL;DR de we have to be 2 or 5 or can we play a 3 in a group??