Ask HN: How to earn trust from users and increase conversion rate

We are operating an app helping people apply visas using their mobile phone (fill forms, submit supporting documents by taking pictures etc.), we have acquired 300+ customers in less than 2 weeks, and 350+ visa applications created, most of the customers stop after the 1st step (Basic personal information), they won't take further step, only 2 users completed the whole process, and they are very happy with our assistance. We believe it's because of lack of trust, people are not willing to give out their private informations, but how could they trust the other traditional agents?