I ended up doing two interviews but I was unable to schedule the face to face due to traveling constrains. You only get a selection of days to choose from and they are quite limited.

First, you have to apply it and submit your application on United website when the flight attendant opposition is opening. Then, you will get an assessment, kinda like a personality test. Second, you will be invited to a virtual interview. basically, you need to answer 8 questions and record your answers. You have 3 attempts to record it.