I received an email with a test assignment. After confirming that I received it, I was sent a password to decrypt it. I was given a week to complete the assignment. It was a CTF-style assignment. I've completed the assignment on day 2, sent everything to them by email in the format described in their explanation doc. 5 days later, when one week time was due, I received an email that they decided not to proceed with my application because they did not receive the completed assignment. I told them I sent it 5 days ago (by the time I received the rejection email) and I was ghosted. In their rejection email they mentioned that they are "in a luxurious position" due to the number of skilled applicants they received, which is a very awful treatment. TLDR: They ignored my completed assignment, used inappropriate and unprofessional language and ghosted me in the end.