NEED ADVICE, JOB OFFERING.

Computer Engineering graduate, i tried to apply into IT officer development position in a state owned bank, i manage to pass all the recruitment process, i was doing pretty bad and had panick attack in the last process of recruitment (user interview), the interviewer talked about all stuff related to mobile app development in banking which i had no any glimpse about, but i told them that i only had some minor experience related to web development and networking, i was pretty sure i would lose against other candidate, one week passed and i suddenly got job offering from them, please give me some advice regarding online mobile app development course (even better if the course was specifically emphasized on mobile app for banking), i previously relied on udemy for my web dev learning.