Where Does Credence Get the Bird?

Later it is revealed that that bird is phoenix and came to him when he was in need. Now, there are two things here. Either Credence is really a brother of Albus and phoenix came to him in need or it was an illusion of Grindelwald. Both are speculation until JK clarifies it or next movie comes.

How did Credence get the Phoenix?

In the very final scene, Grindelwald informs Credence that he is, in fact, Aurelius Dumbledore, Albus and Aberforth's long lost brother. The chick that Credence has been carrying erupts into flame, and transforms into a red-and-gold phoenix.

Is Fawkes a Credences Phoenix?

Is that phoenix Fawkes? In this film, Dumbledore conveniently states for the first time that a phoenix will appear to a Dumbledore in need. When Grindelwald is telling Credence he's a Dumbledore, the small bird Credence has had with him throughout the film is revealed to be a phoenix.