You do not have to transfer tickets to others.
It’s perfectly fine to keep all your tickets on your own phone and bring your group with you.
Gate staff can scan multiple tickets from a single device.
However, if some friends want to use their own phones or you prefer it, you can transfer individual tickets to them via the app.
That way each person can enter on their own phone.
Both options work – transferring is for convenience if others want their own copies.