Purchasing Power, LLC Testing interview questions

Applied for the position online and got initial screening email from HR with list of questions. Replied to the email and no communication thereafter. Even with multiple follow ups, there was no response. I understand that many candidates apply to a position and HR cannot reach out to each and every candidate. However when HR initiates the initial conversation, it is not ethical to drop out the communication abruptly. HR must understand that candidates too spend significant time and effort to apply.