I applied in San Francisco, where there are several branches. Some people apply when they travel through a city with a branch, since there are no geographical (home address) requirements. Bank branches where you can apply are in California: SF (4), Oakland (1), LA area (5), and New York: NYC (3)

They had an online application early on but pulled it soon after. Their website indicates to apply in-branch. I did read a story somewhere where someone managed to apply working with someone in a branch without doing it in-person, so I would suggest calling a branch and asking them if that is possible.